Research Strategies and Validity

1. Research Strategies and Validity Chapter 6 George S. Robinson, Jr., Ph.D. Department of Psychology North Carolina A&T State University

2. Research Strategy • Research strategy • a general approach to research determined by the kind of question that the research study hopes to answer

3. Strategy Types • Descriptive research strategy • describe variables as they exist • Correlational research strategy • looking for the relationship between two variables

4. Strategy Types - cont. • Experimental research strategy • demonstrates a cause-and-effect relationship between two variables • independent variable is manipulated • dependent variable is measured • four basic components of an experiment • manipulation • measurement • comparison • control

5. Strategy Types - cont. • Quasi-experimental strategy • compares groups or conditions but lacks either manipulation or control • (e.g., before and after treatment comparisons, or differences between certain groups based on a particular characteristic)

6. Validity • Validity of a Research Study • determined by the quality of the research process and the accuracy of the results

7. Validity - cont. • Internal validity • produces a single, unambiguous explanation for the results • threats to internal validity • extraneous variables • confounding variables • general threats to internal validity • participant variables • assignment bias • environmental variables • history effects • measurement variables • practice effects • fatigue

8. Validity - cont. • External validity • the extent to which the results can be generalized • threats to external validity • category 1: generalizing across participants or subject • subject selection bias (cost-restrictive sampling) • college students • volunteer bias • participant characteristics • cross-species generalizations

9. Threats to external validity - cont. • category II: generalizing across features of a study • novelty effect • reactivity • laboratory versus field setting • demand characteristics • the good subject role • the negativistic subject role • the faithful subject role • the apprehensive subject role • category III: generalizing across experiments • experimenter bias or experimenter expectancy • experimenter characteristics

10. Threats to external validity - cont. • category IV: generalizing across features of a measure • sensitization or assessment sensitization • generality across response measures • time of measurement

11. Validity and Individual Research Strategies • validity and descriptive strategy • high external validity • low internal validity • validity and correlational strategy • high external validity • low internal validity • validity and experimental strategy • low external validity • high internal validity • validity and quasi-experimental strategy • high external validity • low internal validity

12. Research Strategies, Research Designs, Research Procedures • Research Strategy • the general approach and goals of the research study • Research design • a general plan for implementing a research strategy • group versus individual • same individual versus different individuals • the number of variables to be included • Research procedure • an exact step-by-step description of a specific research study