Research Methodology An Overview Ahmed Mandil Prof of

Research Methodology: An Overview Ahmed Mandil, Prof of Epidemiology King Saud University, Riyadh, KSA

Headlines n n n n Health research Choice of subjects Data collection methods Sources of data Study designs (qualitative, quantitative) Choice of study design Health research proposal Literature review Oct 24, 2009 Research Methodology 2

Health Research n n n Lab research: applies knowledge of basic sciences towards development of procedures and strategies to prevent, control and understand mechanisms of healthrelated phenomena Population-based (field) research: study of distribution, determinants, control measures of health-related phenomena in chosen populations, followed by application of suitable biostatistical techniques which may allow generalization of results Healthcare-facility (clinical) research: application of epidemiological principles in research based in healthcare facilities, e. g. randomized clinical trials Oct 24, 2009 Research Methodology 3

Research Characteristics n n n Has a clearly stated question(s) and hypotheses (null, alternative) Has a specific plan of action Builds on existent knowledge Generates NEW data, which answers the original question(s) Opens horizons for further enquiries and research Oct 24, 2009 Research Methodology 4

Subjects & Data Collection n n Selected Units: individuals, groups Study Populations: cross-sectional, longitudinal Data collection timing: prospectively, retrospectively, combination Data collection types: primary, secondary Oct 24, 2009 Research Methodology 5

Study Populations n n n Cross-sectional: where ONLY ONE set of observations is collected for every unit in the study at a certain point in time, disregarding the length of time of study as a whole (health surveys’ populations are of this type) Longitudinal: where TWO-OR-MORE sets of observations are collected for every unit in the study, i. e. follow up is involved in order to allow monitoring of a certain population (cohort) over a specified period of time. Dynamic: gains and loses members Oct 24, 2009 Research Methodology 6

Data Collection Types n n Primary: where the investigator is the first to collect the data. Sources include: medical examinations, interviews, observations, etc. Merits: less measurement error, suits objectives of the study better. Disadvantage: costly, may not be feasible. Secondary: where the data is collected by OTHERS, for other purposes that those of the current study. Sources include: individual records (medical / employment); group records (census data, vital statistics) Oct 24, 2009 Research Methodology 7

Data Collection Sources n n Routine systems (e. g. vital statistics: births / deaths; health insurance; communicable diseases) Surveys (interviews; telephone; mail; selfadministered) Disease registries (hospital / community – based) Sentinel event recording systems (health; disease; health services) Oct 24, 2009 Research Methodology 8

Study Design: Definition A study design is a specific plan or protocol for conducting the study, which allows the investigator to translate the conceptual hypothesis into an operational one. Oct 24, 2009 Research Methodology 9

Study Designs: Types n n Qualitative Quantitative n Experimental n Observational n Basic n Hybrid n Incomplete Oct 24, 2009 Research Methodology 10

Types of quantitative designs n n Observational designs: studies that do not involve any intervention or experiment. Experimental designs: studies that entail manipulation of the study factor (exposure) and randomization of subjects to treatment (exposure) groups Oct 24, 2009 Research Methodology 11

Observational Designs n n n Exploratory: used when the state of knowledge about the phenomenon is poor: small scale; of limited duration. Descriptive: used to formulate a certain hypothesis: small / large scale. Examples: case-studies; cross-sectional studies Analytical: used to test hypotheses: small / large scale. Examples: case-control, crosssectional, cohort. Oct 24, 2009 Research Methodology 12

Cross-sectional Studies (Community health studies, surveys) n n Characteristics: detects point prevalence; relatively common conditions; allows for stratification; different from surveillance / registers Merits: feasible; quick; economic; allows study of several diseases / exposures; useful for estimation of the population burden, health planning and priority setting of health problems Limitations: temporal ambiguity (cannot determine whether the exposure preceded outcome); possible measurement error; not suitable for rare conditions; liable to survivor bias Effect measure: Odds Ratio + CI Oct 24, 2009 Research Methodology 13

Case - Control Studies n n Characteristics: two source populations; assumption that non-cases are representative of the source population of cases. Merits: least expensive; least time-consuming; suitable for study of rare diseases (especially NCDs) Limitations: not suitable for rare exposures; liable to selection bias and recall bias; not suitable for calculation of frequency measures. Effect measure: Odds Ratio + CI Oct 24, 2009 Research Methodology 14

Cohort Studies n n Characteristics: follow-up period (prospective; retrospective) Merits: no temporal ambiguity; several outcomes could be studied at the same time; suitable for incidence estimation Limitations (of prospective type): expensive; time-consuming; inefficient for rare diseases; may not be feasible Effect measure: Relative Risk + CI Oct 24, 2009 Research Methodology 15

disease Cohort Design Factor present Study population free of disease Factor absent no disease present future time Study begins here Oct 24, 2009 Research Methodology 16

Experimental Designs n n n Types: Lab experiments; Randomized Clinical trials; Community interventions studies. These types are differentiated by: number of participants and duration Merits: control of confounders Limitations: limited generalizability; possibility of unethical randomization; impracticability under some settings Oct 24, 2009 Research Methodology 17

outcome RANDOMIZATION Intervention Experimental Design no outcome Study population outcome Control no outcome baseline future time Study begins here (baseline point) Oct 24, 2009 Research Methodology 18

Choice of Study Design (I) Depends on: n Research Questions n Research Goals n Researcher Beliefs and Values n Researcher Skills n Time and Funds Oct 24, 2009 Research Methodology 19

Choice of Study Design (II) n n n Status of existent knowledge Occurrence of disease Duration of latent period Nature and availability of information Available resources Time constraints Oct 24, 2009 Research Methodology 20

Health Research Proposal Components n n n n n Executive Summary Literature review & rationale Objectives & hypothesis Methodology Ethical considerations Chronogram Budget References Investigating team Oct 24, 2009 Research Methodology 21

What is a good proposal ? n n Credible innovative research question Meticulously designed research plan Carefully selected research team Attractively presenting all of the above, so that it: n Communicates clearly & concisely n Follows a logical outline n Indicates merits and limitations of the plan, but n Makes sure that merits do stand out (for a busy reviewer) Oct 24, 2009 Research Methodology 22

Literature Review n n Peer consultation Databases (search engines: e. g. Pubmed; Medline; Ovid; IMEMR at WHO / EMRO website) n n n Published literature (scientific journals) Published literature (electronic journals) Grey literature (theses: masters / doctoral; reports: ministry of health / social affairs / annual statistics; national census, others) Oct 24, 2009 Research Methodology 23

References 1. 2. 3. 4. 5. Porta M. A dictionary of epidemiology. 5 th edition. Oxford, New York: Oxford University Press, 2008. Fathallah MF, Fathallah MMF. A practical guide for health researchers. Cairo: WHO, 2004. Rothman KF, Greenland S, Lash TL. Modern Epidemiology. 3 rd edition. Philadelphia: Walter Kluwer, Williams & Wilkins 2008: 100 -110. Gordis L. Epidemiology. 4 th edition. Philadelphia, Pennsylvania: Elsevier Science, 2008 Beaglehole R, Bonita R, Kjellstrom T. Basic epidemiolgy. 2 nd edition. Geneva: World Health Organization, 2006 Oct 24, 2009 Research Methodology 24

Thank you for your kind attention Oct 24, 2009 Research Methodology 25