Questions I have had some professors who have

Questions • I have had some professors who have a preference on APA style, is the library website a good source for APA format? Do you have a particular preference? • What are the consequences if a researcher does not behave ethically towards individuals? • How do you determine the sample size in a given research study? • How do you know whether or not the chosen sample is representative of the target population?

More Questions • How do you know if you are inflicting any psychological harm on subjects in animal research? (such as in a controlled lab experiment and not just in observation). • In the abstract of a research report, do you need to separate the sections into background, methods, results, conclusions or can you make it one paragraph? • If a research has to ethically release all information to a participant before an experiment, how can you ethically run a double blind study where the participant has no idea what is being done.

More Questions • How can the way in which results are reported become an ‘ethical issue’ of the research process? • To do a research, you have to take the Ethics code test. Do you have to retake the test for every research study/experiment that you do or do you only have to take it once?

Research strategies and validity Chapter 6 Dusana Rybarova Psyc 290 B May 22 2006

Outline 1. Introduction to research strategies 2. Validity and its threats - internal validity - external validity 3. Research strategies, research designs and research procedures

1. Introduction to research strategies • research strategy – reflects the general approach and goals of a research study • types of research strategies – descriptive strategy – Nonexperimental strategy – correlational strategy – experimental strategy – quasi-experimental strategy

1. Introduction to research strategies • Descriptive strategy – the goal is to describe the state of affairs at the time of the study – measures variables as they exist naturally – e. g. 19% of eligible voters participated in the election • Correlational strategy – measures two variables, usually as they exist naturally – the goal of this strategy is to describe a relationship between the two variables without attempting to explain the cause of the relationship – e. g. Are students GPA’s related to their parent’s income? • Nonexperimental strategy – Answers questions about the relationship between two variables by demonstrating a difference between two groups or two threatment conditions – E. g. verbal scores of 6 -years old boy and 6 -years old girls

1. Introduction to research strategies • Experimental strategy – the researcher manipulates one variable (called independent variable) while observing or measuring a second variable (dependent variable) – this is the ‘true’ experiment because independent variable is manipulated by the researcher (e. g. room temperature) – the goal of experimental strategy is to determine whether a causal relationship exists between two variables

1. Introduction to research strategies • Quasi-experimental strategy – uses a nonmanipulated variable to define groups or conditions (e. g. time or age) or pre and post threatment – controls other variables as much as possible – the goal is to obtain evidence in support of a cause-and-effect relationship – however, a quasi-experimental strategy can not unambiguously establish a causal relationship

2. Validity and its threats • validity is the standard criterion by which researchers judge the quality of research • in this case the concept of validity applies to an entire research study • any component of a research study that introduces questions or raises doubts about the quality of the research process or the accuracy of the research results is a threat to validity

2. Validity and its threats • Internal validity – is concerned with factors within the research study that raise doubts about the results or the interpretation – any factor within the study that allows an alternative explanation for the results is a threat to internal validity – e. g. example with room temperature and performance

2. Validity and its threats • threats to internal validity – Extraneous variables • any variable in a research study other than the two variables being studied (both systematic and unsystematic) – unsystematically changing variables are usually not a problem • confounding variable is an extraneous variable that is allowed to change systematically along with the two variables being studied (e. g. time of the day in the temperature-performance study)

2. Validity and its threats • threats to internal validity – sources of extraneous/confounding variables • participant variables – assignment bias – when the process used to assign different participants to different threatments produces groups of individuals with noticeably different characteristics (e. g. one group is smarter, more motivated) • environmental variables – size of room, time of day, or gender of the experimenter • measurement variables – practice effects – prior exposure to a measurement procedure provides participants with additional skills that produce improved scores (e. g. the same exam) – fatigue – prior participation tires the participants so that their scores on subsequent measurements are lower

2. Validity and its threats • External validity – concerns the extent to which the results obtained in a research study hold true outside the constraints of the study – Can the results be generalized to other populations, other settings, other measurements? – e. g. can we generalize results from a wellcontrolled laboratory situation to the uncontrolled chaos of the real world?

2. Validity and its threats • threats to external validity – Participants • characteristics unique to a specific group of participants in a study may limit ability to generalize the results to individuals with different characteristics – e. g. college students, volunteer bias, cross-species generalizations – Features of the study • characteristics unique to the specific procedures used in a study may limit ability to generalize the results to situations where other procedures are used – e. g. novelty effect, reactivity, specifics of the study (masking experiments, lexical decisions)

2. Validity and its threats • threats to external validity – experimenters • characteristics unique to the specific experimenter conducting the study may limit ability to generalize the results to situations with a different experimenter – e. g. experimenter bias, experimenter characteristics – measurements • characteristics unique to the specific measurement procedure may limit ability to generalize the results to situations where a different measurement procedure is used – e. g. sensitization (the impact of being assessed), generality across different measures (heart beat vs. questionnaire), time of measurement

2. Validity and its threats • Balancing internal and external validity – attempts to increase internal validity can reduce external validity (laboratory experiments) – research that attempts to gain a high level of external validity will often create a research environment that closely resembles the outside world – there tends to be a tradeoff between internal and external validity (if you increase internal validity, external validity decreases a vice versa)

2. Validity and its threats • Validity of individual research strategies – descriptive strategy • high external validity • low internal validity – Nonexperimental strategy • High external validity • Low internal validity – correlational strategy • high external validity • low internal validity

2. Validity and its threats • Validity of individual research strategies – experimental strategy • high internal validity • low external validity – quasi-experimental strategy • higher internal validity than descriptive and correlational studies • lower internal validity than true experiments • relatively high external validity

3. Research strategies, research designs, and research procedures • Research strategy – refers to the general approach and goals of the study • Research design – general plan for implementing a research strategy (e. g. group versus individual, same individuals vs. different individuals, number of variables included) • Research procedure – an exact, step-by-step description of a specific research study (exact involvement of individuals, measurement of variables etc. )