Experimental designs The strongest of the research designs
![Experimental designs The strongest of the research designs Image: www. freeimages. co. uk 1 Experimental designs The strongest of the research designs Image: www. freeimages. co. uk 1](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-1.jpg)
![Categories of research • Quantitative – Involves numerical data that result from taking measurements Categories of research • Quantitative – Involves numerical data that result from taking measurements](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-2.jpg)
![Categories of research (cont. ) • Qualitative – Involves data derived from words e. Categories of research (cont. ) • Qualitative – Involves data derived from words e.](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-3.jpg)
![Quantitative vs. qualitative research • Quantitative research employs the scientific method and is usually Quantitative vs. qualitative research • Quantitative research employs the scientific method and is usually](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-4.jpg)
![Pragmatic and explanatory research • Pragmatic research – Used to verify the effectiveness of Pragmatic and explanatory research • Pragmatic research – Used to verify the effectiveness of](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-5.jpg)
![Pragmatic and explanatory research (cont. ) • Explanatory research – Used to establish the Pragmatic and explanatory research (cont. ) • Explanatory research – Used to establish the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-6.jpg)
![Pragmatic and explanatory research (cont. ) – Patient selection is more strict in explanatory Pragmatic and explanatory research (cont. ) – Patient selection is more strict in explanatory](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-7.jpg)
![Descriptive, relational, and causal research • Descriptive (observational) research – Observes and records various Descriptive, relational, and causal research • Descriptive (observational) research – Observes and records various](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-8.jpg)
![Descriptive, relational, and causal research (cont. ) • Causal research – Explores whether an Descriptive, relational, and causal research (cont. ) • Causal research – Explores whether an](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-9.jpg)
![Experimental and quasiexperimental research • Experimental research – Random assignment to groups is involved Experimental and quasiexperimental research • Experimental research – Random assignment to groups is involved](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-10.jpg)
![Experimental and quasiexperimental research (cont. ) • Non-experimental research – Does not involve random Experimental and quasiexperimental research (cont. ) • Non-experimental research – Does not involve random](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-11.jpg)
![Research design notation • • R – random assignment O – observation or measure Research design notation • • R – random assignment O – observation or measure](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-12.jpg)
![Research designs • A quasi-experiment – 2 groups but no randomization • Non-experiment – Research designs • A quasi-experiment – 2 groups but no randomization • Non-experiment –](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-13.jpg)
![Population • The units from which a sample is drawn – May include people, Population • The units from which a sample is drawn – May include people,](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-14.jpg)
![Samples • Samples can permit inferences about what is happening in a population based Samples • Samples can permit inferences about what is happening in a population based](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-15.jpg)
![Sample selection A sample is selected Evidence-based Chiropractic 16 © 2006 Sample selection A sample is selected Evidence-based Chiropractic 16 © 2006](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-16.jpg)
![Samples (cont. ) • Population parameters that are estimated from random samples are known Samples (cont. ) • Population parameters that are estimated from random samples are known](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-17.jpg)
![Samples (cont. ) • Selection criteria in clinical trials – Patients are usually included Samples (cont. ) • Selection criteria in clinical trials – Patients are usually included](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-18.jpg)
![Random assignment • Clinical trials often employ random assignment (a. k. a. , randomization) Random assignment • Clinical trials often employ random assignment (a. k. a. , randomization)](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-19.jpg)
![Random assignment (cont. ) • Blocking – Subjects are separated into homogeneous subgroups based Random assignment (cont. ) • Blocking – Subjects are separated into homogeneous subgroups based](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-20.jpg)
![Random assignment (cont. ) • Stratified randomization – Intact groups are separated into subgroups Random assignment (cont. ) • Stratified randomization – Intact groups are separated into subgroups](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-21.jpg)
![Random assignment (cont. ) • Concealment – Assignment is often concealed from researchers to Random assignment (cont. ) • Concealment – Assignment is often concealed from researchers to](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-22.jpg)
![Sample size determination • Articles about clinical trials should discuss why the number of Sample size determination • Articles about clinical trials should discuss why the number of](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-23.jpg)
![Sample size determination (cont. ) • Too few subjects reduces the power of a Sample size determination (cont. ) • Too few subjects reduces the power of a](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-24.jpg)
![The randomized controlled trial (RCT) • Regarded as the ultimate research design in health The randomized controlled trial (RCT) • Regarded as the ultimate research design in health](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-25.jpg)
![Placebo • An inert substance or treatment – Compared to the active substance or Placebo • An inert substance or treatment – Compared to the active substance or](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-26.jpg)
![Sham • A non-therapeutic intervention that imitates the real treatment – Similar to placebo, Sham • A non-therapeutic intervention that imitates the real treatment – Similar to placebo,](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-27.jpg)
![Treatment effect • The result that a treatment has on outcomes that is attributable Treatment effect • The result that a treatment has on outcomes that is attributable](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-28.jpg)
![Why patients improve • Natural history – Many acute and some chronic pain conditions Why patients improve • Natural history – Many acute and some chronic pain conditions](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-29.jpg)
![Components of treatment Evidence-based Chiropractic 30 © 2006 Components of treatment Evidence-based Chiropractic 30 © 2006](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-30.jpg)
![Effectiveness of a treatment • Both the placebo and treatment groups typically improve • Effectiveness of a treatment • Both the placebo and treatment groups typically improve •](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-31.jpg)
![Bias • Systematic errors in a study that are caused by problems with – Bias • Systematic errors in a study that are caused by problems with –](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-32.jpg)
![Hawthorne effect • People tend to react differently when participating in experiments • Researchers Hawthorne effect • People tend to react differently when participating in experiments • Researchers](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-33.jpg)
![Hawthorne effect (cont. ) • Behavior was more influenced by the attention researchers gave Hawthorne effect (cont. ) • Behavior was more influenced by the attention researchers gave](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-34.jpg)
![Types of bias • Sampling bias (a. k. a, selection bias) – During the Types of bias • Sampling bias (a. k. a, selection bias) – During the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-35.jpg)
![Types of bias (cont). – Random assignment with concealment is the best safeguard against Types of bias (cont). – Random assignment with concealment is the best safeguard against](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-36.jpg)
![Types of bias (cont). • Experimenter (researcher) bias – Examining or treating doctors may Types of bias (cont). • Experimenter (researcher) bias – Examining or treating doctors may](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-37.jpg)
![Types of bias (cont). • Exclusion bias – Occurs when patients who drop out Types of bias (cont). • Exclusion bias – Occurs when patients who drop out](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-38.jpg)
![Extraneous and confounding variables • In experiments, researchers are able to manipulate the explanatory Extraneous and confounding variables • In experiments, researchers are able to manipulate the explanatory](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-39.jpg)
![Extraneous and confounding variables (cont. ) • Extraneous variables – Uncontrolled factors that can Extraneous and confounding variables (cont. ) • Extraneous variables – Uncontrolled factors that can](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-40.jpg)
![Extraneous and confounding variables (cont. ) – Error variance due to extraneous variables is Extraneous and confounding variables (cont. ) – Error variance due to extraneous variables is](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-41.jpg)
![Extraneous and confounding variables (cont. ) – The effect of a confounding variable cannot Extraneous and confounding variables (cont. ) – The effect of a confounding variable cannot](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-42.jpg)
![Extraneous and confounding variables (cont. ) • Quasi-experimental designs are particularly susceptible to confounding Extraneous and confounding variables (cont. ) • Quasi-experimental designs are particularly susceptible to confounding](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-43.jpg)
![Threats to internal validity • History – Participants are unintentionally exposed to some historical Threats to internal validity • History – Participants are unintentionally exposed to some historical](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-44.jpg)
![Threats to internal validity (cont. ) • Reliability of measures – Unreliable measures can Threats to internal validity (cont. ) • Reliability of measures – Unreliable measures can](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-45.jpg)
![Threats to internal validity (cont. ) • Mortality – Subjects dropping out of studies Threats to internal validity (cont. ) • Mortality – Subjects dropping out of studies](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-46.jpg)
![Threats to internal validity (cont. ) • Maturation – Changes that occur in study Threats to internal validity (cont. ) • Maturation – Changes that occur in study](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-47.jpg)
![Threats to internal validity (cont. ) • Regression to the mean – Extreme scores Threats to internal validity (cont. ) • Regression to the mean – Extreme scores](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-48.jpg)
![Read and bring to class Monday 11/3/08 • Hoiriis et al. A Randomized Clinical Read and bring to class Monday 11/3/08 • Hoiriis et al. A Randomized Clinical](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-49.jpg)
![External validity a. k. a. , generalizability • The extent results of a study External validity a. k. a. , generalizability • The extent results of a study](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-50.jpg)
![External validity (cont. ) • Meade et al. study – Office-based chiropractic care was External validity (cont. ) • Meade et al. study – Office-based chiropractic care was](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-51.jpg)
![Internal validity vs. external validity Evidence-based Chiropractic 52 © 2006 Internal validity vs. external validity Evidence-based Chiropractic 52 © 2006](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-52.jpg)
![Group Mean vs. an Individual Patient • A RCT only considers the average of Group Mean vs. an Individual Patient • A RCT only considers the average of](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-53.jpg)
![Research designs • The pretest-posttest randomized experimental design – Is the classic experiment design Research designs • The pretest-posttest randomized experimental design – Is the classic experiment design](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-54.jpg)
![Classic experiment design (cont. ) – Subjects are evaluated before and after the intervention Classic experiment design (cont. ) – Subjects are evaluated before and after the intervention](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-55.jpg)
![ANCOVA test The ANCOVA test factors in pretreatment differences between groups as a covariate ANCOVA test The ANCOVA test factors in pretreatment differences between groups as a covariate](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-56.jpg)
![ANCOVA test • Statistically removes the effect of covariates from the analysis • Other ANCOVA test • Statistically removes the effect of covariates from the analysis • Other](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-57.jpg)
![Two-group pretest-posttest design • Comparison with an alternate form of treatment – e. g. Two-group pretest-posttest design • Comparison with an alternate form of treatment – e. g.](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-58.jpg)
![Post-test only randomized controlled trial • Groups cannot be compared after randomization because no Post-test only randomized controlled trial • Groups cannot be compared after randomization because no](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-59.jpg)
![Factorial design • Often used when several explanatory variables are involved in a study Factorial design • Often used when several explanatory variables are involved in a study](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-60.jpg)
![Factorial design (cont. ) • Two factor by two level (2 X 2) factorial Factorial design (cont. ) • Two factor by two level (2 X 2) factorial](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-61.jpg)
![Factorial design (cont. ) – Group 1 received Diversified technique and palpation as the Factorial design (cont. ) – Group 1 received Diversified technique and palpation as the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-62.jpg)
![Crossover design • Treatment is provided to one group, while the other group receives Crossover design • Treatment is provided to one group, while the other group receives](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-63.jpg)
![Crossover design (cont. ) • Each subject acts as their own control, which can Crossover design (cont. ) • Each subject acts as their own control, which can](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-64.jpg)
![Crossover design (cont. ) Crossover design notation R R O O Evidence-based Chiropractic X Crossover design (cont. ) Crossover design notation R R O O Evidence-based Chiropractic X](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-65.jpg)
![Crossover design (cont. ) • Crossover design limitations – Carry-over effects • The therapeutic Crossover design (cont. ) • Crossover design limitations – Carry-over effects • The therapeutic](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-66.jpg)
![Crossover design (cont. ) – Treatment sequencing • Patients may respond differently when treatment Crossover design (cont. ) – Treatment sequencing • Patients may respond differently when treatment](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-67.jpg)
![Quasi-experimental designs • Very similar to the randomized designs, minus random assignment to groups Quasi-experimental designs • Very similar to the randomized designs, minus random assignment to groups](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-68.jpg)
![Non-experimental designs • Do not utilize randomization or a comparison group • Are not Non-experimental designs • Do not utilize randomization or a comparison group • Are not](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-69.jpg)
![Non-experimental designs (cont. ) • Non-experimental designs are low on the evidentiary scale – Non-experimental designs (cont. ) • Non-experimental designs are low on the evidentiary scale –](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-70.jpg)
![Chiropractic interventions and experimental methods • Pharmaceutical experiments work well – Because it is Chiropractic interventions and experimental methods • Pharmaceutical experiments work well – Because it is](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-71.jpg)
![Chiropractic interventions and experimental methods (cont. ) – Patients may actually receive a treatment Chiropractic interventions and experimental methods (cont. ) – Patients may actually receive a treatment](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-72.jpg)
![Ethics in research • Biomedical research ethics came about as a result of abuse Ethics in research • Biomedical research ethics came about as a result of abuse](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-73.jpg)
![Ethics in research (cont. ) • The Nuremberg Code (1947) – Developed from the Ethics in research (cont. ) • The Nuremberg Code (1947) – Developed from the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-74.jpg)
![Ethics in research (cont. ) • Declaration of Helsinki (1964) – Developed by the Ethics in research (cont. ) • Declaration of Helsinki (1964) – Developed by the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-75.jpg)
![Ethics in research (cont. ) • The Belmont Report (1979) – Included 3 principles Ethics in research (cont. ) • The Belmont Report (1979) – Included 3 principles](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-76.jpg)
![Informed consent • Nuremberg Code – “. . . the voluntary consent of the Informed consent • Nuremberg Code – “. . . the voluntary consent of the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-77.jpg)
![Informed consent (cont. ) • Signed informed consent must be obtained from every research Informed consent (cont. ) • Signed informed consent must be obtained from every research](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-78.jpg)
![Informed consent (cont. ) • The consent document should explain – The purpose of Informed consent (cont. ) • The consent document should explain – The purpose of](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-79.jpg)
![Placebo effects • Placebo is Latin for “I will please” • Refers to any Placebo effects • Placebo is Latin for “I will please” • Refers to any](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-80.jpg)
![Placebo American Heritage Dictionary 1. A substance containing no medication and prescribed or given Placebo American Heritage Dictionary 1. A substance containing no medication and prescribed or given](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-81.jpg)
![Placebo effects (cont. ) • Interestingly, some people get better in the placebo group Placebo effects (cont. ) • Interestingly, some people get better in the placebo group](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-82.jpg)
![Sham • The term “sham treatment” is often used instead of placebo • Definition: Sham • The term “sham treatment” is often used instead of placebo • Definition:](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-83.jpg)
![Placebo effects (cont. ) • The placebo effect is triggered by the patient's belief Placebo effects (cont. ) • The placebo effect is triggered by the patient's belief](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-84.jpg)
![Factors that influence the placebo effect • Characteristics of the placebo – If the Factors that influence the placebo effect • Characteristics of the placebo – If the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-85.jpg)
![Factors that influence (cont. ) • Attitude of the patient – If the person Factors that influence (cont. ) • Attitude of the patient – If the person](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-86.jpg)
![Factors that influence (cont. ) • Doctor-patient relationship – If the person trusts their Factors that influence (cont. ) • Doctor-patient relationship – If the person trusts their](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-87.jpg)
![Placebo effects (cont. ) • Types of placebos – Pills are well-known for their Placebo effects (cont. ) • Types of placebos – Pills are well-known for their](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-88.jpg)
![Psychic surgery Is actually produced by sleight of hand Animal tissue and blood are Psychic surgery Is actually produced by sleight of hand Animal tissue and blood are](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-89.jpg)
![How placebos work • Self-limiting disorders – Many conditions are self-limiting (e. g. , How placebos work • Self-limiting disorders – Many conditions are self-limiting (e. g. ,](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-90.jpg)
![How placebos work (cont. ) • Remission – The symptoms of some disorders, such How placebos work (cont. ) • Remission – The symptoms of some disorders, such](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-91.jpg)
![How placebos work (cont. ) • Changes in behavior – The placebo may increase How placebos work (cont. ) • Changes in behavior – The placebo may increase](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-92.jpg)
![How placebos work (cont. ) • Reduced anxiety – Taking the placebo and expecting How placebos work (cont. ) • Reduced anxiety – Taking the placebo and expecting](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-93.jpg)
![How placebos work (cont. ) • Altered brain state – Research has shown that How placebos work (cont. ) • Altered brain state – Research has shown that](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-94.jpg)
![Placebo examples • A meta-analysis of studies of depressed individuals taking antidepressant medications suggests Placebo examples • A meta-analysis of studies of depressed individuals taking antidepressant medications suggests](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-95.jpg)
![Placebo examples (cont. ) • In a survey of surgery for lumbar disc disease, Placebo examples (cont. ) • In a survey of surgery for lumbar disc disease,](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-96.jpg)
![Placebo examples (cont. ) • Moseley et al did a double-blinded, randomized, placebo-controlled trial Placebo examples (cont. ) • Moseley et al did a double-blinded, randomized, placebo-controlled trial](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-97.jpg)
![Placebo examples (cont. ) • Forty years ago, a young Seattle cardiologist named Leonard Placebo examples (cont. ) • Forty years ago, a young Seattle cardiologist named Leonard](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-98.jpg)
![Sham v. Pill • Kaptchuk et al. Sham device v inert pill: randomised controlled Sham v. Pill • Kaptchuk et al. Sham device v inert pill: randomised controlled](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-99.jpg)
![Evidence-based Chiropractic 100 © 2006 Evidence-based Chiropractic 100 © 2006](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-100.jpg)
![Waiting list, where Hawthorne effects, natural progression of the disease, and regression to the Waiting list, where Hawthorne effects, natural progression of the disease, and regression to the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-101.jpg)
![Placebo Death? Evidence-based Chiropractic 102 © 2006 Placebo Death? Evidence-based Chiropractic 102 © 2006](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-102.jpg)
![Natural history of a disease vs. placebo effect • The body has a natural Natural history of a disease vs. placebo effect • The body has a natural](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-103.jpg)
![Why is this important? • Placebo effects, disease natural history, and regression to the Why is this important? • Placebo effects, disease natural history, and regression to the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-104.jpg)
![Appraising research • The objective of appraisal is to assist readers in determining – Appraising research • The objective of appraisal is to assist readers in determining –](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-105.jpg)
![Appraising research (cont. ) • Appraisal should be tailored to the particular research design Appraising research (cont. ) • Appraisal should be tailored to the particular research design](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-106.jpg)
![Three issues to consider 1. Are the results of the study valid? – The Three issues to consider 1. Are the results of the study valid? – The](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-107.jpg)
![Three issues to consider (cont. ) 3. Will the results of the study help Three issues to consider (cont. ) 3. Will the results of the study help](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-108.jpg)
![General Appraisal Checklist • Determine to what extent a study satisfies each point of General Appraisal Checklist • Determine to what extent a study satisfies each point of](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-109.jpg)
![General Appraisal Checklist (cont. ) • The purpose of the study was conveyed plainly General Appraisal Checklist (cont. ) • The purpose of the study was conveyed plainly](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-110.jpg)
![General Appraisal Checklist (cont. ) • The target population was identified. • A determination General Appraisal Checklist (cont. ) • The target population was identified. • A determination](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-111.jpg)
![General Appraisal Checklist (cont. ) • The data were reported with sufficient detail. • General Appraisal Checklist (cont. ) • The data were reported with sufficient detail. •](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-112.jpg)
![General Appraisal Checklist (cont. ) • Study limitations were listed. • Was there any General Appraisal Checklist (cont. ) • Study limitations were listed. • Was there any](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-113.jpg)
![General Appraisal Checklist (cont. ) • Overall impression about the trustworthiness of this article: General Appraisal Checklist (cont. ) • Overall impression about the trustworthiness of this article:](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-114.jpg)
- Slides: 114
![Experimental designs The strongest of the research designs Image www freeimages co uk 1 Experimental designs The strongest of the research designs Image: www. freeimages. co. uk 1](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-1.jpg)
Experimental designs The strongest of the research designs Image: www. freeimages. co. uk 1 © 2006
![Categories of research Quantitative Involves numerical data that result from taking measurements Categories of research • Quantitative – Involves numerical data that result from taking measurements](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-2.jpg)
Categories of research • Quantitative – Involves numerical data that result from taking measurements on subjects – Is objective – Deductive reasoning • Is used to test theories or ideas to determine whether or not they are true – The researcher is an objective observer Evidence-based Chiropractic 2 Image: www. freeimages. co. uk © 2006
![Categories of research cont Qualitative Involves data derived from words e Categories of research (cont. ) • Qualitative – Involves data derived from words e.](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-3.jpg)
Categories of research (cont. ) • Qualitative – Involves data derived from words e. g. , questionnaires or interviews – Is subjective – Inductive reasoning • Reasoning based on observations which are used to create an idea or theory – The researcher actively involved at times Evidence-based Chiropractic 3 © 2006
![Quantitative vs qualitative research Quantitative research employs the scientific method and is usually Quantitative vs. qualitative research • Quantitative research employs the scientific method and is usually](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-4.jpg)
Quantitative vs. qualitative research • Quantitative research employs the scientific method and is usually regarded at a higher level – But may have limited relevance to clinical practice because of strict methods • Qualitative research often leads to quantitative studies • Both forms of research are important Evidence-based Chiropractic 4 © 2006
![Pragmatic and explanatory research Pragmatic research Used to verify the effectiveness of Pragmatic and explanatory research • Pragmatic research – Used to verify the effectiveness of](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-5.jpg)
Pragmatic and explanatory research • Pragmatic research – Used to verify the effectiveness of treatments • i. e. , whether they work under real-life conditions – Does not determine how or why the treatments work – Typically used to help make decisions about the effectiveness of new treatments compared with existing treatments Evidence-based Chiropractic 5 © 2006
![Pragmatic and explanatory research cont Explanatory research Used to establish the Pragmatic and explanatory research (cont. ) • Explanatory research – Used to establish the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-6.jpg)
Pragmatic and explanatory research (cont. ) • Explanatory research – Used to establish the efficacy of treatments • i. e. , how they work under ideal conditions, as in a controlled experiment – Capable of answering questions about how and why treatments work – Strict methods involved are often very different from day-to-day clinical practice • Consequently, results may not be relevant to practitioners Evidence-based Chiropractic 6 © 2006
![Pragmatic and explanatory research cont Patient selection is more strict in explanatory Pragmatic and explanatory research (cont. ) – Patient selection is more strict in explanatory](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-7.jpg)
Pragmatic and explanatory research (cont. ) – Patient selection is more strict in explanatory studies – Patients are excluded because of things like co-morbid conditions, prior treatment, severity of the condition, age, etc. – This may be a disadvantage because it is not known whether the treatment will work for patients in everyday practice • Patients commonly present with many of the exclusion criteria Evidence-based Chiropractic 7 © 2006
![Descriptive relational and causal research Descriptive observational research Observes and records various Descriptive, relational, and causal research • Descriptive (observational) research – Observes and records various](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-8.jpg)
Descriptive, relational, and causal research • Descriptive (observational) research – Observes and records various aspects of participants in a study – Descriptive statistics involved • Relational research – Considers relationships that may exist between variables – Correlation and regression Evidence-based Chiropractic 8 © 2006
![Descriptive relational and causal research cont Causal research Explores whether an Descriptive, relational, and causal research (cont. ) • Causal research – Explores whether an](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-9.jpg)
Descriptive, relational, and causal research (cont. ) • Causal research – Explores whether an intervention causes or affects one or more outcome variables – The most demanding type of research that involves very detailed methods – Looks for statistically significant differences between groups Evidence-based Chiropractic 9 © 2006
![Experimental and quasiexperimental research Experimental research Random assignment to groups is involved Experimental and quasiexperimental research • Experimental research – Random assignment to groups is involved](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-10.jpg)
Experimental and quasiexperimental research • Experimental research – Random assignment to groups is involved – Capable of determining cause-and-effect relationships • Quasi-experimental research – No random assignment – Provides much less evidence about causeand-effect relationships Evidence-based Chiropractic 10 © 2006
![Experimental and quasiexperimental research cont Nonexperimental research Does not involve random Experimental and quasiexperimental research (cont. ) • Non-experimental research – Does not involve random](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-11.jpg)
Experimental and quasiexperimental research (cont. ) • Non-experimental research – Does not involve random assignment or even a comparison group – Merely involves the observation of one group before and after an intervention Evidence-based Chiropractic 11 © 2006
![Research design notation R random assignment O observation or measure Research design notation • • R – random assignment O – observation or measure](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-12.jpg)
Research design notation • • R – random assignment O – observation or measure X – treatment or intervention N – non-equivalent groups • The classic experiment – Randomization and 2 groups Evidence-based Chiropractic R R O O X O O Each row represents a group Time 12 © 2006
![Research designs A quasiexperiment 2 groups but no randomization Nonexperiment Research designs • A quasi-experiment – 2 groups but no randomization • Non-experiment –](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-13.jpg)
Research designs • A quasi-experiment – 2 groups but no randomization • Non-experiment – Only 1 group Evidence-based Chiropractic 13 N N O O O X X O O O © 2006
![Population The units from which a sample is drawn May include people Population • The units from which a sample is drawn – May include people,](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-14.jpg)
Population • The units from which a sample is drawn – May include people, but can also consist of events or observations • It is rarely possible to include each and every unit of a population – Instead, a smaller number of units (a sample) are selected to represent the entire population • Defined as a subset of observations from a population Evidence-based Chiropractic 14 © 2006
![Samples Samples can permit inferences about what is happening in a population based Samples • Samples can permit inferences about what is happening in a population based](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-15.jpg)
Samples • Samples can permit inferences about what is happening in a population based on what is observed in a sample • However, the sample must be representative of the population – Often achieved through random selection of the sample units whereby each unit of the population has an equal chance of being selected Evidence-based Chiropractic 15 © 2006
![Sample selection A sample is selected Evidencebased Chiropractic 16 2006 Sample selection A sample is selected Evidence-based Chiropractic 16 © 2006](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-16.jpg)
Sample selection A sample is selected Evidence-based Chiropractic 16 © 2006
![Samples cont Population parameters that are estimated from random samples are known Samples (cont. ) • Population parameters that are estimated from random samples are known](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-17.jpg)
Samples (cont. ) • Population parameters that are estimated from random samples are known as unbiased estimates • Random sampling is rarely employed in clinical trials – Patients are obtained using sequentially presenting patients or recruiting through advertisements – Referred to as convenience sampling Evidence-based Chiropractic 17 © 2006
![Samples cont Selection criteria in clinical trials Patients are usually included Samples (cont. ) • Selection criteria in clinical trials – Patients are usually included](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-18.jpg)
Samples (cont. ) • Selection criteria in clinical trials – Patients are usually included in a clinical trial only if they meet certain criteria – e. g. , severity of the condition, no secondary conditions, history, age, etc. • It is important to consider features of the population in a study when applying its results to a specific patient Evidence-based Chiropractic 18 © 2006
![Random assignment Clinical trials often employ random assignment a k a randomization Random assignment • Clinical trials often employ random assignment (a. k. a. , randomization)](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-19.jpg)
Random assignment • Clinical trials often employ random assignment (a. k. a. , randomization) – Refers to the way patients are assigned to groups • Used to make groups equivalent regarding prognostic factors (e. g. , pain levels) – Sometimes called probabilistic equivalence because there is still a chance the groups will be a different after randomization Evidence-based Chiropractic 19 © 2006
![Random assignment cont Blocking Subjects are separated into homogeneous subgroups based Random assignment (cont. ) • Blocking – Subjects are separated into homogeneous subgroups based](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-20.jpg)
Random assignment (cont. ) • Blocking – Subjects are separated into homogeneous subgroups based on factors such as age or disease severity – Enhances comparison because the subgroups are more alike than the intact groups Evidence-based Chiropractic 20 © 2006
![Random assignment cont Stratified randomization Intact groups are separated into subgroups Random assignment (cont. ) • Stratified randomization – Intact groups are separated into subgroups](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-21.jpg)
Random assignment (cont. ) • Stratified randomization – Intact groups are separated into subgroups based on prognostic factors – e. g. , trauma vs. non-trauma patients in a whiplash study Evidence-based Chiropractic 21 © 2006
![Random assignment cont Concealment Assignment is often concealed from researchers to Random assignment (cont. ) • Concealment – Assignment is often concealed from researchers to](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-22.jpg)
Random assignment (cont. ) • Concealment – Assignment is often concealed from researchers to avoid the temptation of allotting patients with certain traits to groups that will receive special treatment • When concealment is inadequate, the apparent effects of the treatment may be distorted as much as or more than the size of the effect being investigated Evidence-based Chiropractic 22 © 2006
![Sample size determination Articles about clinical trials should discuss why the number of Sample size determination • Articles about clinical trials should discuss why the number of](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-23.jpg)
Sample size determination • Articles about clinical trials should discuss why the number of subjects was chosen • Ethically important – Because no more subjects should be inconvenienced or put at risk than required to find a treatment effect • Economically – Extra resources required to include unnecessary subjects Evidence-based Chiropractic 23 © 2006
![Sample size determination cont Too few subjects reduces the power of a Sample size determination (cont. ) • Too few subjects reduces the power of a](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-24.jpg)
Sample size determination (cont. ) • Too few subjects reduces the power of a study so that a treatment effect may not be noticeable when it actually is present • Extremely large samples may show statistically significant differences between groups that are so small they are not clinically important Evidence-based Chiropractic 24 © 2006
![The randomized controlled trial RCT Regarded as the ultimate research design in health The randomized controlled trial (RCT) • Regarded as the ultimate research design in health](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-25.jpg)
The randomized controlled trial (RCT) • Regarded as the ultimate research design in health care • The classic experiment Evidence-based Chiropractic 25 © 2006
![Placebo An inert substance or treatment Compared to the active substance or Placebo • An inert substance or treatment – Compared to the active substance or](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-26.jpg)
Placebo • An inert substance or treatment – Compared to the active substance or treatment in RCTs – Used in pharmaceutical trials to establish whether an active drug is more effective than a placebo – The drug and placebo groups are compared to determine if the drug resulted in a statistically significant treatment effect Evidence-based Chiropractic 26 © 2006
![Sham A nontherapeutic intervention that imitates the real treatment Similar to placebo Sham • A non-therapeutic intervention that imitates the real treatment – Similar to placebo,](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-27.jpg)
Sham • A non-therapeutic intervention that imitates the real treatment – Similar to placebo, but refers to something done rather than something taken – Patients should have a very difficult time telling the difference between a sham and the real treatment – A sham chiropractic manipulation is difficult to produce Evidence-based Chiropractic 27 © 2006
![Treatment effect The result that a treatment has on outcomes that is attributable Treatment effect • The result that a treatment has on outcomes that is attributable](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-28.jpg)
Treatment effect • The result that a treatment has on outcomes that is attributable specifically to the effect of the intervention • The difference between the mean outcomes observed in a treatment group and a control group Evidence-based Chiropractic 28 © 2006
![Why patients improve Natural history Many acute and some chronic pain conditions Why patients improve • Natural history – Many acute and some chronic pain conditions](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-29.jpg)
Why patients improve • Natural history – Many acute and some chronic pain conditions resolve on their own • Actual effect of the treatment • Nonspecific effects of the treatment – Linked to the treatment, but actually due to factors other than the active components of the treatment – Sometimes called placebo effects Evidence-based Chiropractic 29 © 2006
![Components of treatment Evidencebased Chiropractic 30 2006 Components of treatment Evidence-based Chiropractic 30 © 2006](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-30.jpg)
Components of treatment Evidence-based Chiropractic 30 © 2006
![Effectiveness of a treatment Both the placebo and treatment groups typically improve Effectiveness of a treatment • Both the placebo and treatment groups typically improve •](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-31.jpg)
Effectiveness of a treatment • Both the placebo and treatment groups typically improve • The difference between groups at the conclusion of the study is what matters • The treatment is considered effective if the mean outcome of the treatment group is significantly better than the placebo group Evidence-based Chiropractic 31 © 2006
![Bias Systematic errors in a study that are caused by problems with Bias • Systematic errors in a study that are caused by problems with –](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-32.jpg)
Bias • Systematic errors in a study that are caused by problems with – The selection or assignment of patients to groups – The measurements involved in the study • Bias can render a study invalid, although all studies have at least some bias Evidence-based Chiropractic 32 © 2006
![Hawthorne effect People tend to react differently when participating in experiments Researchers Hawthorne effect • People tend to react differently when participating in experiments • Researchers](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-33.jpg)
Hawthorne effect • People tend to react differently when participating in experiments • Researchers found that the productivity of workers increased when they new they were involved in a study – True under a variety of conditions – Even conditions that should have reduced productivity Evidence-based Chiropractic 33 © 2006
![Hawthorne effect cont Behavior was more influenced by the attention researchers gave Hawthorne effect (cont. ) • Behavior was more influenced by the attention researchers gave](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-34.jpg)
Hawthorne effect (cont. ) • Behavior was more influenced by the attention researchers gave to the subjects than the effect of the interventions • The Hawthorne effect is a factor in all clinical studies Evidence-based Chiropractic 34 © 2006
![Types of bias Sampling bias a k a selection bias During the Types of bias • Sampling bias (a. k. a, selection bias) – During the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-35.jpg)
Types of bias • Sampling bias (a. k. a, selection bias) – During the selection process, each person does not have an equal chance of being selected from the source population – Random selection is designed to take care of this problem – Results in systematic differences between groups in experimental studies as to factors of prognosis or response to treatment Evidence-based Chiropractic 35 © 2006
![Types of bias cont Random assignment with concealment is the best safeguard against Types of bias (cont). – Random assignment with concealment is the best safeguard against](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-36.jpg)
Types of bias (cont). – Random assignment with concealment is the best safeguard against selection bias in RCTs – The effect of selection bias is reduced by random assignment because it distributes the bias evenly between the treatment and control groups Evidence-based Chiropractic 36 © 2006
![Types of bias cont Experimenter researcher bias Examining or treating doctors may Types of bias (cont). • Experimenter (researcher) bias – Examining or treating doctors may](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-37.jpg)
Types of bias (cont). • Experimenter (researcher) bias – Examining or treating doctors may influence a study’s results because of their expectancies or desires for a certain outcome – Blinding (masking) of researchers and study participants as to group assignment can diminish the effect of this bias – This bias can be divided into detection bias and performance bias Evidence-based Chiropractic 37 © 2006
![Types of bias cont Exclusion bias Occurs when patients who drop out Types of bias (cont). • Exclusion bias – Occurs when patients who drop out](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-38.jpg)
Types of bias (cont). • Exclusion bias – Occurs when patients who drop out of a study are systematically different from subjects who remain • Perhaps dropouts were having a poor response to treatment • Would have changed the results of the study if they had remained Evidence-based Chiropractic 38 © 2006
![Extraneous and confounding variables In experiments researchers are able to manipulate the explanatory Extraneous and confounding variables • In experiments, researchers are able to manipulate the explanatory](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-39.jpg)
Extraneous and confounding variables • In experiments, researchers are able to manipulate the explanatory variables and then watch what happens to the outcome variable • Internal validity – The ability of an experiment to show that the explanatory variables actually caused the observed changes in the outcome variables Evidence-based Chiropractic 39 © 2006
![Extraneous and confounding variables cont Extraneous variables Uncontrolled factors that can Extraneous and confounding variables (cont. ) • Extraneous variables – Uncontrolled factors that can](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-40.jpg)
Extraneous and confounding variables (cont. ) • Extraneous variables – Uncontrolled factors that can influence the relationship between variables in an experiment – They are not the variables that are being studied, yet they affect the outcome of the experiment – They are unwanted because they create error Evidence-based Chiropractic 40 © 2006
![Extraneous and confounding variables cont Error variance due to extraneous variables is Extraneous and confounding variables (cont. ) – Error variance due to extraneous variables is](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-41.jpg)
Extraneous and confounding variables (cont. ) – Error variance due to extraneous variables is distributed evenly between the groups when random assignment is utilized • Confounding variable – A type of extraneous variable that affects the explanatory variables differently • e. g. , it affects the treatment group but not the control group – Introduces systematic error into the study Evidence-based Chiropractic 41 © 2006
![Extraneous and confounding variables cont The effect of a confounding variable cannot Extraneous and confounding variables (cont. ) – The effect of a confounding variable cannot](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-42.jpg)
Extraneous and confounding variables (cont. ) – The effect of a confounding variable cannot be separated from the outcome variable Explanatory variable e. g. , manipulation Outcome variable e. g. , low back pain Confounding variable e. g. , groups receive manual vs. instrument manipulation Evidence-based Chiropractic 42 © 2006
![Extraneous and confounding variables cont Quasiexperimental designs are particularly susceptible to confounding Extraneous and confounding variables (cont. ) • Quasi-experimental designs are particularly susceptible to confounding](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-43.jpg)
Extraneous and confounding variables (cont. ) • Quasi-experimental designs are particularly susceptible to confounding because the individual differences of subjects may act as confounding variables • For example – A quasi-experimental study that assigned headache patients with more severe pain to the treatment group Evidence-based Chiropractic 43 © 2006
![Threats to internal validity History Participants are unintentionally exposed to some historical Threats to internal validity • History – Participants are unintentionally exposed to some historical](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-44.jpg)
Threats to internal validity • History – Participants are unintentionally exposed to some historical event during the research project which affects the results – For example • A statewide fitness campaign that coincides with a lower back pain study • Some of the subjects doing the exercises would likely affect the study’s outcome Evidence-based Chiropractic 44 © 2006
![Threats to internal validity cont Reliability of measures Unreliable measures can Threats to internal validity (cont. ) • Reliability of measures – Unreliable measures can](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-45.jpg)
Threats to internal validity (cont. ) • Reliability of measures – Unreliable measures can invalidate a study – Possible causes • Faulty equipment, inconsistent instructions to study participants, unreliable training of examiners, fatigue or boredom of examiners, or examiners becoming more skilled at doing the test Evidence-based Chiropractic 45 © 2006
![Threats to internal validity cont Mortality Subjects dropping out of studies Threats to internal validity (cont. ) • Mortality – Subjects dropping out of studies](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-46.jpg)
Threats to internal validity (cont. ) • Mortality – Subjects dropping out of studies – Drop-outs may be different from those who remain – Occurs for a variety of reasons • e. g. , poor response to treatment, exceptional response to treatment, adverse effects – Groups may not be equivalent as a result Evidence-based Chiropractic 46 © 2006
![Threats to internal validity cont Maturation Changes that occur in study Threats to internal validity (cont. ) • Maturation – Changes that occur in study](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-47.jpg)
Threats to internal validity (cont. ) • Maturation – Changes that occur in study participants as time passes that are not caused by the explanatory variables – e. g. , in a study investigating strength in children, they would most likely get stronger in time, even without exposure to the explanatory variables Evidence-based Chiropractic 47 © 2006
![Threats to internal validity cont Regression to the mean Extreme scores Threats to internal validity (cont. ) • Regression to the mean – Extreme scores](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-48.jpg)
Threats to internal validity (cont. ) • Regression to the mean – Extreme scores at the beginning of a study that migrate toward the mean as time passes – Occurs because extreme symptoms tend to return to a more normal state on their own • i. e. , high initial patient scores are much more likely to move toward normality than to go even higher – Especially problematic when patients are selected based on high test values, while patients with low values are screened out Evidence-based Chiropractic 48 © 2006
![Read and bring to class Monday 11308 Hoiriis et al A Randomized Clinical Read and bring to class Monday 11/3/08 • Hoiriis et al. A Randomized Clinical](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-49.jpg)
Read and bring to class Monday 11/3/08 • Hoiriis et al. A Randomized Clinical Trial Comparing Chiropractic Adjustments To Muscle Relaxants For Subacute Low Back Pain. JMPT 2004; 27: 388 -98 • Bakris, et al. Atlas vertebra realignment and achievement of arterial pressure goal in hypertensive patients: a pilot study. J Hum Hypertens. 2007 May; 21(5): 347 -52. Evidence-based Chiropractic 49 © 2006
![External validity a k a generalizability The extent results of a study External validity a. k. a. , generalizability • The extent results of a study](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-50.jpg)
External validity a. k. a. , generalizability • The extent results of a study are applicable to other populations, other settings, and when implemented under different circumstances – Should be comparable regarding the intervention, age, condition severity, etc. • Relating to EBP – Are the results of a study applicable to the management of a particular patient? Evidence-based Chiropractic 50 © 2006
![External validity cont Meade et al study Officebased chiropractic care was External validity (cont. ) • Meade et al. study – Office-based chiropractic care was](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-51.jpg)
External validity (cont. ) • Meade et al. study – Office-based chiropractic care was compared with hospital-based physical therapy for low back pain – Chiropractic was found to be superior, but may have been related to patients being treated in private chiropractic offices versus out-patient PT departments at hospitals Evidence-based Chiropractic 51 © 2006
![Internal validity vs external validity Evidencebased Chiropractic 52 2006 Internal validity vs. external validity Evidence-based Chiropractic 52 © 2006](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-52.jpg)
Internal validity vs. external validity Evidence-based Chiropractic 52 © 2006
![Group Mean vs an Individual Patient A RCT only considers the average of Group Mean vs. an Individual Patient • A RCT only considers the average of](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-53.jpg)
Group Mean vs. an Individual Patient • A RCT only considers the average of a group of subjects • A given patient will NOT be average – Each patient is unique in some way regarding condition severity, secondary conditions, response to care, etc. • Each practitioner is unique with a whole arsenal of treatment options Evidence-based Chiropractic 53 © 2006
![Research designs The pretestposttest randomized experimental design Is the classic experiment design Research designs • The pretest-posttest randomized experimental design – Is the classic experiment design](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-54.jpg)
Research designs • The pretest-posttest randomized experimental design – Is the classic experiment design mentioned earlier • The most commonly used design in research – Patients are randomized to treatment groups which drastically reduces the chance of bias Evidence-based Chiropractic 54 © 2006
![Classic experiment design cont Subjects are evaluated before and after the intervention Classic experiment design (cont. ) – Subjects are evaluated before and after the intervention](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-55.jpg)
Classic experiment design (cont. ) – Subjects are evaluated before and after the intervention so that pre-treatment differences between groups can be considered • Groups are rarely exactly equivalent • Analysis of covariance (ANCOVA) test factors in pretreatment differences between groups as a covariate – Use of a control group allows separation of the active ingredient of the treatment effect from non-specific components Evidence-based Chiropractic 55 © 2006
![ANCOVA test The ANCOVA test factors in pretreatment differences between groups as a covariate ANCOVA test The ANCOVA test factors in pretreatment differences between groups as a covariate](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-56.jpg)
ANCOVA test The ANCOVA test factors in pretreatment differences between groups as a covariate Evidence-based Chiropractic 56 © 2006
![ANCOVA test Statistically removes the effect of covariates from the analysis Other ANCOVA test • Statistically removes the effect of covariates from the analysis • Other](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-57.jpg)
ANCOVA test • Statistically removes the effect of covariates from the analysis • Other variables can also be “adjusted for” using ANCOVA – e. g. , differences between groups regarding age or condition severity • Example report in journal article –. . . the effects of pre-treatment differences were adjusted for during analysis Evidence-based Chiropractic 57 © 2006
![Twogroup pretestposttest design Comparison with an alternate form of treatment e g Two-group pretest-posttest design • Comparison with an alternate form of treatment – e. g.](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-58.jpg)
Two-group pretest-posttest design • Comparison with an alternate form of treatment – e. g. , a new therapy is compared to an established therapy – Cannot determine whether a new treatment works better than no treatment R R Evidence-based Chiropractic O O X 1 X 2 58 O O © 2006
![Posttest only randomized controlled trial Groups cannot be compared after randomization because no Post-test only randomized controlled trial • Groups cannot be compared after randomization because no](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-59.jpg)
Post-test only randomized controlled trial • Groups cannot be compared after randomization because no pretest is used – It is a weaker design because of doubts about the success of randomization • Sometimes used when groups are large – Large groups are much more likely to be equivalent R R Evidence-based Chiropractic X 59 O O © 2006
![Factorial design Often used when several explanatory variables are involved in a study Factorial design • Often used when several explanatory variables are involved in a study](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-60.jpg)
Factorial design • Often used when several explanatory variables are involved in a study • Useful to determine if any interaction exists between the variables • Explanatory variables are categorized as – Factors (the major independent variables) – Levels (subgroups) Evidence-based Chiropractic 60 © 2006
![Factorial design cont Two factor by two level 2 X 2 factorial Factorial design (cont. ) • Two factor by two level (2 X 2) factorial](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-61.jpg)
Factorial design (cont. ) • Two factor by two level (2 X 2) factorial design X 11 X 21 Evidence-based Chiropractic 61 X 12 X 22 © 2006
![Factorial design cont Group 1 received Diversified technique and palpation as the Factorial design (cont. ) – Group 1 received Diversified technique and palpation as the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-62.jpg)
Factorial design (cont. ) – Group 1 received Diversified technique and palpation as the method of analysis – Group 2 Gonstead and palpation – Group 3 Diversified and x-ray – Group 4 Gonstead and x-ray Factorial design notation Evidence-based Chiropractic R R O O 62 X 11 X 12 X 21 X 22 O O © 2006
![Crossover design Treatment is provided to one group while the other group receives Crossover design • Treatment is provided to one group, while the other group receives](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-63.jpg)
Crossover design • Treatment is provided to one group, while the other group receives a placebo or alternate treatment • Group assignments are switched at some point in time without the doctors’ or subjects’ knowledge • Each group receives both the active treatment and the alternate treatment Evidence-based Chiropractic 63 © 2006
![Crossover design cont Each subject acts as their own control which can Crossover design (cont. ) • Each subject acts as their own control, which can](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-64.jpg)
Crossover design (cont. ) • Each subject acts as their own control, which can reduce the required sample size considerably Evidence-based Chiropractic 64 © 2006
![Crossover design cont Crossover design notation R R O O Evidencebased Chiropractic X Crossover design (cont. ) Crossover design notation R R O O Evidence-based Chiropractic X](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-65.jpg)
Crossover design (cont. ) Crossover design notation R R O O Evidence-based Chiropractic X 1 X 2 O O Optional washout period 65 O O X 2 X 1 O O © 2006
![Crossover design cont Crossover design limitations Carryover effects The therapeutic Crossover design (cont. ) • Crossover design limitations – Carry-over effects • The therapeutic](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-66.jpg)
Crossover design (cont. ) • Crossover design limitations – Carry-over effects • The therapeutic effects of the first intervention continue during the second intervention – High dropout rates • Because there are 2 or more periods of treatment • The negative effect is more harmful to the data analysis than other designs because each patient’s data is so important Evidence-based Chiropractic 66 © 2006
![Crossover design cont Treatment sequencing Patients may respond differently when treatment Crossover design (cont. ) – Treatment sequencing • Patients may respond differently when treatment](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-67.jpg)
Crossover design (cont. ) – Treatment sequencing • Patients may respond differently when treatment 1 is given before treatment 2 than if the order is reversed – For example • A chronic neck pain study where treatment 1 is manipulation and treatment 2 is massage • Results may be different if treatment 2 is provided first because the massage may enable patients to receive a better effect from the manipulation Evidence-based Chiropractic 67 © 2006
![Quasiexperimental designs Very similar to the randomized designs minus random assignment to groups Quasi-experimental designs • Very similar to the randomized designs, minus random assignment to groups](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-68.jpg)
Quasi-experimental designs • Very similar to the randomized designs, minus random assignment to groups • The lack of randomization is a major factor that make claims about causality based on quasi-experimental evidence doubtful • On the other hand, a first-rate quasiexperiment can generate stronger evidence than a poorly conducted RCT Evidence-based Chiropractic 68 © 2006
![Nonexperimental designs Do not utilize randomization or a comparison group Are not Non-experimental designs • Do not utilize randomization or a comparison group • Are not](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-69.jpg)
Non-experimental designs • Do not utilize randomization or a comparison group • Are not capable of determining the effect of an intervention • Includes – Survey and observational research – Case studies and case series Evidence-based Chiropractic 69 © 2006
![Nonexperimental designs cont Nonexperimental designs are low on the evidentiary scale Non-experimental designs (cont. ) • Non-experimental designs are low on the evidentiary scale –](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-70.jpg)
Non-experimental designs (cont. ) • Non-experimental designs are low on the evidentiary scale – They are still quite valuable because they describe unfamiliar occurrences and often lead to more complex studies • Pretreatment measures may be taken, but usually one measure is involved X Evidence-based Chiropractic O 70 © 2006
![Chiropractic interventions and experimental methods Pharmaceutical experiments work well Because it is Chiropractic interventions and experimental methods • Pharmaceutical experiments work well – Because it is](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-71.jpg)
Chiropractic interventions and experimental methods • Pharmaceutical experiments work well – Because it is fairly easy to make an active pill and an identical looking placebo pill • Not so with chiropractic interventions – It is difficult to deceive doctors and patients – Sham adjustments are either so invasive they become therapeutic or so dissimilar from adjustments that patients know they are in the placebo group Evidence-based Chiropractic 71 © 2006
![Chiropractic interventions and experimental methods cont Patients may actually receive a treatment Chiropractic interventions and experimental methods (cont. ) – Patients may actually receive a treatment](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-72.jpg)
Chiropractic interventions and experimental methods (cont. ) – Patients may actually receive a treatment effect when sham adjustments are too invasive – Conversely, they may not receive a placebo effect when they are aware of their inclusion in the placebo group Evidence-based Chiropractic 72 © 2006
![Ethics in research Biomedical research ethics came about as a result of abuse Ethics in research • Biomedical research ethics came about as a result of abuse](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-73.jpg)
Ethics in research • Biomedical research ethics came about as a result of abuse to research participants in the past – Nazis concentration camp experiments – The Tuskegee Syphilis Study – Research was often carried out on prisoners, orphans, or mentally ill; many times without the subjects’ knowledge Evidence-based Chiropractic 73 © 2006
![Ethics in research cont The Nuremberg Code 1947 Developed from the Ethics in research (cont. ) • The Nuremberg Code (1947) – Developed from the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-74.jpg)
Ethics in research (cont. ) • The Nuremberg Code (1947) – Developed from the Nuremberg Military Tribunals – Had no legal authority (unenforceable) – Only dealt with research on healthy participants – Left the control of research entirely up to scientists Evidence-based Chiropractic 74 © 2006
![Ethics in research cont Declaration of Helsinki 1964 Developed by the Ethics in research (cont. ) • Declaration of Helsinki (1964) – Developed by the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-75.jpg)
Ethics in research (cont. ) • Declaration of Helsinki (1964) – Developed by the World Medical Association to remedy deficiencies of the Nuremberg Code – Has been amended five times, most recently in 2000 – Required medical researchers to clearly define study protocols – Protocols had to be submitted to independent ethical review committees (IRB) for approval Evidence-based Chiropractic 75 © 2006
![Ethics in research cont The Belmont Report 1979 Included 3 principles Ethics in research (cont. ) • The Belmont Report (1979) – Included 3 principles](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-76.jpg)
Ethics in research (cont. ) • The Belmont Report (1979) – Included 3 principles of research ethics • Autonomy – the principle of respect for persons; especially those with diminished autonomy • Beneficence – supports the well-being of research subjects by maximizing benefits while minimizing harms • Justice – the distribution of the benefits, burdens, and risks of research should be equitable between societal groups Evidence-based Chiropractic 76 © 2006
![Informed consent Nuremberg Code the voluntary consent of the Informed consent • Nuremberg Code – “. . . the voluntary consent of the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-77.jpg)
Informed consent • Nuremberg Code – “. . . the voluntary consent of the human subject is absolutely essential. ” • Belmont Report – Respect for research participants – Research subjects must be given the opportunity to choose what shall or shall not happen to them Evidence-based Chiropractic 77 © 2006
![Informed consent cont Signed informed consent must be obtained from every research Informed consent (cont. ) • Signed informed consent must be obtained from every research](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-78.jpg)
Informed consent (cont. ) • Signed informed consent must be obtained from every research participant – However, it is a process, not just a form – The document should be thought of as a teaching tool, not as a legal instrument • The document must be written in “lay language” that is understandable to the people being asked to participate Evidence-based Chiropractic 78 © 2006
![Informed consent cont The consent document should explain The purpose of Informed consent (cont. ) • The consent document should explain – The purpose of](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-79.jpg)
Informed consent (cont. ) • The consent document should explain – The purpose of the research – The benefits and risks – Confidentiality matters – A study contact person if questions arise – That participation is voluntary and subjects have the right to withdraw at any time – How adverse events are dealt with Evidence-based Chiropractic 79 © 2006
![Placebo effects Placebo is Latin for I will please Refers to any Placebo effects • Placebo is Latin for “I will please” • Refers to any](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-80.jpg)
Placebo effects • Placebo is Latin for “I will please” • Refers to any type of treatment that is inert • Used in research trials to objectively test the efficacy of new treatments • One group is given the treatment, while another group (the control group) receives a placebo • Comparing the results from both groups should reveal the effects of the treatment Evidence-based Chiropractic 80 © 2006
![Placebo American Heritage Dictionary 1 A substance containing no medication and prescribed or given Placebo American Heritage Dictionary 1. A substance containing no medication and prescribed or given](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-81.jpg)
Placebo American Heritage Dictionary 1. A substance containing no medication and prescribed or given to reinforce a patient's expectation to get well 2. An inactive substance or preparation used as a control in an experiment or test to determine the effectiveness of a medicinal drug 3. Something of no intrinsic remedial value that is used to appease or reassure another Evidence-based Chiropractic 81 © 2006
![Placebo effects cont Interestingly some people get better in the placebo group Placebo effects (cont. ) • Interestingly, some people get better in the placebo group](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-82.jpg)
Placebo effects (cont. ) • Interestingly, some people get better in the placebo group • This phenomenon is known as “the placebo effect” • The placebo effect is substantial – About one third of people taking placebos for a number of complaints will experience relief • The underlying mechanisms remain a mystery Evidence-based Chiropractic 82 © 2006
![Sham The term sham treatment is often used instead of placebo Definition Sham • The term “sham treatment” is often used instead of placebo • Definition:](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-83.jpg)
Sham • The term “sham treatment” is often used instead of placebo • Definition: – Something false or empty that is purported to be genuine; a spurious imitation Evidence-based Chiropractic 83 © 2006
![Placebo effects cont The placebo effect is triggered by the patients belief Placebo effects (cont. ) • The placebo effect is triggered by the patient's belief](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-84.jpg)
Placebo effects (cont. ) • The placebo effect is triggered by the patient's belief in the treatment and their expectation of feeling better • If symptoms are relieved by taking an inert substance or undergoing a dummy procedure, was the original illness imaginary? • No Evidence-based Chiropractic 84 © 2006
![Factors that influence the placebo effect Characteristics of the placebo If the Factors that influence the placebo effect • Characteristics of the placebo – If the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-85.jpg)
Factors that influence the placebo effect • Characteristics of the placebo – If the pill (or treatment) looks genuine, the person taking it is more likely to believe that it contains active ingredients – Larger sized pills suggest a stronger dose than smaller pills, and taking two pills appears more potent than just one – Injections have a more powerful effect than pills Evidence-based Chiropractic 85 © 2006
![Factors that influence cont Attitude of the patient If the person Factors that influence (cont. ) • Attitude of the patient – If the person](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-86.jpg)
Factors that influence (cont. ) • Attitude of the patient – If the person expects the treatment to work, the chances of a placebo effect are higher – However, the placebo effect may still take place even if the person is skeptical of success – The power of suggestion is probably at work here Evidence-based Chiropractic 86 © 2006
![Factors that influence cont Doctorpatient relationship If the person trusts their Factors that influence (cont. ) • Doctor-patient relationship – If the person trusts their](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-87.jpg)
Factors that influence (cont. ) • Doctor-patient relationship – If the person trusts their health care practitioner, they are more likely to believe that the placebo will work – Chiropractors typically instill more trust in their patients, consequently critics have pointed to this as a likely explanation of our successes Evidence-based Chiropractic 87 © 2006
![Placebo effects cont Types of placebos Pills are wellknown for their Placebo effects (cont. ) • Types of placebos – Pills are well-known for their](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-88.jpg)
Placebo effects (cont. ) • Types of placebos – Pills are well-known for their placebo effect – However, a placebo can be any inert or “dummy” treatment – Special diets, exercise, physical therapy or surgery – Even chiropractic manipulation Evidence-based Chiropractic 88 © 2006
![Psychic surgery Is actually produced by sleight of hand Animal tissue and blood are Psychic surgery Is actually produced by sleight of hand Animal tissue and blood are](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-89.jpg)
Psychic surgery Is actually produced by sleight of hand Animal tissue and blood are used to give a realistic appearance, while a patient's fleshy midriff helps create the illusion that the surgeon's fingers have actually penetrated the body Still practiced today in Brazil and the Philippines Evidence-based Chiropractic 89 © 2006
![How placebos work Selflimiting disorders Many conditions are selflimiting e g How placebos work • Self-limiting disorders – Many conditions are self-limiting (e. g. ,](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-90.jpg)
How placebos work • Self-limiting disorders – Many conditions are self-limiting (e. g. , common cold, some back or neck pain) – They will resolve on their own with or without treatment – Symptoms resolving is merely coincidence Evidence-based Chiropractic 90 © 2006
![How placebos work cont Remission The symptoms of some disorders such How placebos work (cont. ) • Remission – The symptoms of some disorders, such](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-91.jpg)
How placebos work (cont. ) • Remission – The symptoms of some disorders, such as multiple sclerosis and lupus, may wax and wane – A remission during a course of placebos may be coincidence, and not due to the placebos at all Evidence-based Chiropractic 91 © 2006
![How placebos work cont Changes in behavior The placebo may increase How placebos work (cont. ) • Changes in behavior – The placebo may increase](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-92.jpg)
How placebos work (cont. ) • Changes in behavior – The placebo may increase a person’s motivation to take better care of themselves, which may be responsible for the easing of their symptoms • Altered perception – The person’s interpretation of their symptoms may change with the expectation of feeling better. (e. g. , a sharp pain being reinterpreted as an uncomfortable tingling) Evidence-based Chiropractic 92 © 2006
![How placebos work cont Reduced anxiety Taking the placebo and expecting How placebos work (cont. ) • Reduced anxiety – Taking the placebo and expecting](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-93.jpg)
How placebos work (cont. ) • Reduced anxiety – Taking the placebo and expecting to feel better may soothe autonomic nervous system reducing levels of stress chemicals • Brain chemicals – Placebos may trigger the brain to release endorphins, the body's own natural painkillers Evidence-based Chiropractic 93 © 2006
![How placebos work cont Altered brain state Research has shown that How placebos work (cont. ) • Altered brain state – Research has shown that](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-94.jpg)
How placebos work (cont. ) • Altered brain state – Research has shown that the brain responds to an imagined scene in much the same way it responds to an actual visualized scene. Placebos may help the brain to remember a time before the onset of symptoms, and then bring about physiological change – The so-called “remembered wellness” theory Evidence-based Chiropractic 94 © 2006
![Placebo examples A metaanalysis of studies of depressed individuals taking antidepressant medications suggests Placebo examples • A meta-analysis of studies of depressed individuals taking antidepressant medications suggests](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-95.jpg)
Placebo examples • A meta-analysis of studies of depressed individuals taking antidepressant medications suggests that approximately: – One quarter of the drug response is due to the administration of an active medication – One half is a placebo effect –Listening to Prozac but Hearing Placebo: A Meta. The remaining quarter is due to other Analysis of Antidepressant Medication. Prevention & nonspecific factors Treatment, Volume 1, Article 0002 a, June 26, 1998 Evidence-based Chiropractic 95 © 2006
![Placebo examples cont In a survey of surgery for lumbar disc disease Placebo examples (cont. ) • In a survey of surgery for lumbar disc disease,](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-96.jpg)
Placebo examples (cont. ) • In a survey of surgery for lumbar disc disease, although no disc herniation was present in 346 patients (negative surgical exploration), complete relief of sciatica occurred in 37 percent and from back pain in 43 percent Evidence-based Chiropractic 96 © 2006
![Placebo examples cont Moseley et al did a doubleblinded randomized placebocontrolled trial Placebo examples (cont. ) • Moseley et al did a double-blinded, randomized, placebo-controlled trial](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-97.jpg)
Placebo examples (cont. ) • Moseley et al did a double-blinded, randomized, placebo-controlled trial to compare arthroscopic lavage and debridement vs. a sham procedure • They found that all three treatment groups fared equally: subjective symptomatic relief was reported, but no objective improvement in function in any of the groups Evidence-based Chiropractic 97 © 2006
![Placebo examples cont Forty years ago a young Seattle cardiologist named Leonard Placebo examples (cont. ) • Forty years ago, a young Seattle cardiologist named Leonard](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-98.jpg)
Placebo examples (cont. ) • Forty years ago, a young Seattle cardiologist named Leonard Cobb conducted a unique trial of a procedure then commonly used for angina, in which doctors made small incisions in the chest and tied knots in two arteries to try to increase blood flow to the heart. It was a popular technique and 90 percent of patients reported that it helped, but when Cobb compared it with placebo surgery in which he made incisions but did not tie off the arteries, the sham operations proved just as successful. The procedure, known as internal mammary ligation, was soon abandoned – "The Placebo Prescription" by Margaret Talbot, New York Times Magazine, January 9, 2000 Evidence-based Chiropractic 98 © 2006
![Sham v Pill Kaptchuk et al Sham device v inert pill randomised controlled Sham v. Pill • Kaptchuk et al. Sham device v inert pill: randomised controlled](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-99.jpg)
Sham v. Pill • Kaptchuk et al. Sham device v inert pill: randomised controlled trial of two placebo treatments. BMJ 2006; 332: 391 -397. – Fake acupuncture and sugar pills were tested for their effect on relieving arm pain – Both groups noticed improvements, but fake acupuncture was significantly better – 25% of acupuncture group noticed side effects and 3 of the sugar pill group actually withdrew because of them Evidence-based Chiropractic 99 © 2006
![Evidencebased Chiropractic 100 2006 Evidence-based Chiropractic 100 © 2006](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-100.jpg)
Evidence-based Chiropractic 100 © 2006
![Waiting list where Hawthorne effects natural progression of the disease and regression to the Waiting list, where Hawthorne effects, natural progression of the disease, and regression to the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-101.jpg)
Waiting list, where Hawthorne effects, natural progression of the disease, and regression to the mean could be observed “Limited” interaction that involved placebo treatment plus minimal patient-practitioner interaction “Augmented” interaction that also involved a placebo treatment, plus a defined positive patient-practitioner relationship. Evidence-based Chiropractic © 2006 Kaptchuk T. Components of placebo effect: randomised controlled trial in patients 101 with irritable bowel syndrome. BMJ. 2008 May 3; 336
![Placebo Death Evidencebased Chiropractic 102 2006 Placebo Death? Evidence-based Chiropractic 102 © 2006](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-102.jpg)
Placebo Death? Evidence-based Chiropractic 102 © 2006
![Natural history of a disease vs placebo effect The body has a natural Natural history of a disease vs. placebo effect • The body has a natural](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-103.jpg)
Natural history of a disease vs. placebo effect • The body has a natural ability to heal itself and people heal spontaneously, occasionally even when the illness is serious • Hard to differentiate from placebo effect • Cases of spontaneous remission sometimes end up being regarded as miracles Evidence-based Chiropractic 103 © 2006
![Why is this important Placebo effects disease natural history and regression to the Why is this important? • Placebo effects, disease natural history, and regression to the](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-104.jpg)
Why is this important? • Placebo effects, disease natural history, and regression to the mean can result in high rates of good outcomes, which may be falsely ascribed to specific treatment effects • The true causes of improvements in pain after treatment remain unknown in the absence of independently evaluated randomized controlled trials Evidence-based Chiropractic 104 © 2006
![Appraising research The objective of appraisal is to assist readers in determining Appraising research • The objective of appraisal is to assist readers in determining –](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-105.jpg)
Appraising research • The objective of appraisal is to assist readers in determining – The extent a study is valid – Whether its findings are applicable to a given clinical situation • Involves judging the degree a study complied with proper research methodology Evidence-based Chiropractic 105 © 2006
![Appraising research cont Appraisal should be tailored to the particular research design Appraising research (cont. ) • Appraisal should be tailored to the particular research design](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-106.jpg)
Appraising research (cont. ) • Appraisal should be tailored to the particular research design being evaluated • It is essential for readers to be familiar with the various designs that are commonly used Evidence-based Chiropractic 106 © 2006
![Three issues to consider 1 Are the results of the study valid The Three issues to consider 1. Are the results of the study valid? – The](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-107.jpg)
Three issues to consider 1. Are the results of the study valid? – The study methodology should be acceptable – Statements should be logical and supported by the study’s findings – Confounding factors 2. What are the results of the study? – If a treatment effect is present, consider whether it is clinically significant Evidence-based Chiropractic 107 © 2006
![Three issues to consider cont 3 Will the results of the study help Three issues to consider (cont. ) 3. Will the results of the study help](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-108.jpg)
Three issues to consider (cont. ) 3. Will the results of the study help my patients? – The study’s findings should be applicable to your practice or to one of your patients Evidence-based Chiropractic 108 © 2006
![General Appraisal Checklist Determine to what extent a study satisfies each point of General Appraisal Checklist • Determine to what extent a study satisfies each point of](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-109.jpg)
General Appraisal Checklist • Determine to what extent a study satisfies each point of the checklist – Yes Partly No • After appraisal, decide whether to use the information in your practice – Unfortunately, there are no strict rules to base this decision on – It is essentially a judgment call Evidence-based Chiropractic 109 © 2006
![General Appraisal Checklist cont The purpose of the study was conveyed plainly General Appraisal Checklist (cont. ) • The purpose of the study was conveyed plainly](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-110.jpg)
General Appraisal Checklist (cont. ) • The purpose of the study was conveyed plainly and rationally. • A suitable literature review was presented that adequately covered the topic. • The research design was clearly described. • The research design was in concordance with the study question. • The research design was adequately implemented. Evidence-based Chiropractic 110 © 2006
![General Appraisal Checklist cont The target population was identified A determination General Appraisal Checklist (cont. ) • The target population was identified. • A determination](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-111.jpg)
General Appraisal Checklist (cont. ) • The target population was identified. • A determination of the needed sample size was carried out. • The sample size was adequate. • Subjects were randomly assigned to groups. • Groups were equivalent. • Data collection methods were adequately described and were appropriate. • Demographic characteristics of the groups were presented. Evidence-based Chiropractic 111 © 2006
![General Appraisal Checklist cont The data were reported with sufficient detail General Appraisal Checklist (cont. ) • The data were reported with sufficient detail. •](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-112.jpg)
General Appraisal Checklist (cont. ) • The data were reported with sufficient detail. • Statistical tests were described and were appropriate for the type of data involved. • The discussion corresponded to and was supported by the data. • Discussion statements were reasonable and logical. • Conclusions were in agreement with the study’s predetermined purpose. Evidence-based Chiropractic 112 © 2006
![General Appraisal Checklist cont Study limitations were listed Was there any General Appraisal Checklist (cont. ) • Study limitations were listed. • Was there any](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-113.jpg)
General Appraisal Checklist (cont. ) • Study limitations were listed. • Was there any evidence of a “fishing expedition”? • References were accurate and appropriately used. • References were from respected evidence sources. Evidence-based Chiropractic 113 © 2006
![General Appraisal Checklist cont Overall impression about the trustworthiness of this article General Appraisal Checklist (cont. ) • Overall impression about the trustworthiness of this article:](https://slidetodoc.com/presentation_image_h/2f9dc10170c1bedff221ba654c35d5ad/image-114.jpg)
General Appraisal Checklist (cont. ) • Overall impression about the trustworthiness of this article: Good – Accept all or most of the article’s findings. Fair – Cautiously accept some of its findings. Poor – Do not accept any of its findings. • If acceptable, how will I apply the results to my patient/practice? – Consider generalizability and clinical significance issues Evidence-based Chiropractic 114 © 2006
Experimental vs non experimental research
Quasi-experimental research designs
Quasi-experimental research designs
Research instrument in experimental research
Research instrument in experimental research
Experimental vs non experimental
Solomon four group design
Experimental vs non experimental
Nonexperimental study
Strongest research design
Basic principles of experimental designs
Matched-pair design
Design meaning in research
Basic principles of experimental design
Characteristics of experimental research design
Non experimental research topics
Quasi experiment disadvantages
What is basic research
Mini research report
Intra subject counterbalancing
Non experimental research correlational design
Experimental research
Descriptive vs correlational vs experimental research
Case control vs retrospective cohort
Characteristics of experimental research design
Experimental research steps
Matching by holding variables constant
2x3 within subjects design
Proposal penelitian eksperimen psikologi
Non-experimental quantitative research
Experimental research design types
Experimental design and ethical considerations
Comparative vs. correlational
Operational definition of anger
What is a research design
Quasi experiment
What is quasi experimental research
Examples of operational definition
Field experiment
Chapter 4 experimental research
Qualitative paper example
Categories of research design
Basic research designs
Chapter 10 qualitative research designs
Types of qualitative designs
Types of action research design
Types of research empirical vs
Descriptive correlation research
Exploratory, descriptive and causal research
Causal research example
Conclusive research methodology
Main features of qualitative research
Characteristics of exploratory research
Research designs
Exploratory research vs conclusive research
A transition metal used in incandescent light bulbs
The strongest one
Reducing agent
Strongest reducing agent
Lets try this towers of papers
Intramolecular forces vs intermolecular
Dipole dipole interaction example
Strongest to weakest intermolecular forces
Intermolecular forces from strongest to weakest
Convenience form in cavity preparation
Besides faithfulness to god what is the strongest value
Strongest bridge design popsicle sticks
Bridges webquest
Weak acid concentration
How to tell which is the strongest acid
Who is the world's strongest man
Nno lewis structure
The strongest one
Chicago, illinois (latitude 42°n) is located in the ____.
Trituration definition in dentistry
Beowulf hero archetype
Classification of chisel
What was the strongest influence on the enlightenment
Dagon god
Synthetic fiber types
What is the strongest shape
Strongest intramolecular force
What is the strongest acid
Paper towel absorbency facts
ساختار لوویس no+
Where does hydrogen bonding occur
The strongest muscle contractions are normally achieved by
The strongest plant cells are
Which covalent molecule has the strongest bond o-f n=n o=o
Hát kết hợp bộ gõ cơ thể
Frameset trong html5
Bổ thể
Tỉ lệ cơ thể trẻ em
Gấu đi như thế nào
Tư thế worm breton là gì
Chúa yêu trần thế alleluia
Các môn thể thao bắt đầu bằng từ đua
Thế nào là hệ số cao nhất
Các châu lục và đại dương trên thế giới
Cong thức tính động năng
Trời xanh đây là của chúng ta thể thơ
Cách giải mật thư tọa độ
Phép trừ bù
Phản ứng thế ankan
Các châu lục và đại dương trên thế giới
Thể thơ truyền thống
Quá trình desamine hóa có thể tạo ra
Một số thể thơ truyền thống
Bàn tay mà dây bẩn
Vẽ hình chiếu vuông góc của vật thể sau
Nguyên nhân của sự mỏi cơ sinh 8
đặc điểm cơ thể của người tối cổ
Thế nào là giọng cùng tên? *
Vẽ hình chiếu đứng bằng cạnh của vật thể
Phối cảnh