PSY 231 Research Methods in Psychology

1. PSY 231Research Methods in Psychology Non-true-experimental Designs, cont.

2. Announcements • Journal Article Summary #2 (or research participation alternative) due in labs this week • bring results from group projects to lab • GAs will go over plans of analyses with you

3. today • Chapter 12—The Correlational Research Strategy • Chapter 13—The Descriptive Research Strategy • Chapter 10—The Nonexperimental and Quasi-Experimental Strategies: Nonequivalent Group, Pre-Post, and Developmental Designs • Chapter 14—Single-Subject Research Designs • Chapter 15—Statistical Evaluation of Data

4. balance of the validities • internal—extent to which a research study produces a single, unambiguous explanation for the relationships between two variables • external—extent to which we can generalize the results of a research study to people, settings, times, measures, and characteristics other than those in that study • balance depends on level of experimental control

5. threats to internal validity • assignment bias • history • maturation • instrumentation • testing effects

6. nonexperimental research vs. quasi-experimental research • nonexperimental—intended to demonstrate a relationship between variables but does not attempt to explain • quasi-experimental—uses some rigor and control of true experiments but contains a flaw that prevents cause-effect • remember—true experiments include • a control group • manipulation of independent variable(s) • random assignment to groups

7. nonexperimental research vs. quasi-experimental research • both use comparisons between groups or conditions • both use nonmanipulated independent variables • attempts to control internal validity threats • nonexperimental—no • quasi-experimental—yes

8. nonexperimental research vs. quasi-experimental research • two types • between-subjects designs • nonequivalent groups • within-subjects designs • pre-post designs

9. nonequivalent groups designs • posttest-only nonequivalent groups • assignment bias, no control of time effects • nonexperimental participantsprogram measure participants no program measure

10. example smoker participants training program measure smokers no training program measure

11. nonequivalent groups designs • pretest-posttest nonequivalent control design • assignment bias, some control of time effects • quasi-experimental participants measure program measure participants measure no program measure

12. example no t.v. aggression aggression participants measure t.v. measure t.v. aggression aggression participants measure (no change) measure

13. pre-post designs • one-group pretest-posttest design • little control of time effects • nonexperimental participants measure program measure

14. example smoker participants measure program measure

15. pre-post designs • time-series design • some control of time effects • quasi-experimental measure measure measure measure program measure measure measure measure

16. example 1951 1952 1953 1954 1955 1959 1958 1957 1956

17. developmental designs • nonmanipulated independent variable—age or time • three types • cross-sectional • longitudinal • sequential

18. cross-sectional design • different participants, at different ages, studied at same time

19. cross-sectional design • advantages • time efficient • no long-term cooperation • disadvantages • no individual changes • cohort effects

20. longitudinal design • same participants, at different ages, studied at different times

21. longitudinal design • advantages • no cohort effects • assesses individual changes • disadvantages • time consuming • long-term cooperation

22. sequential design • different participants, at different ages, studied at different times

23. single-subject designs • originally used in behavior modification • often seen in clinical and applied settings • not used very often in traditional research

24. single-subject designs • different from traditional designs • usually conducted with one person or a small group • much more flexible • require continuous assessment

25. single-subject designs • baseline observations—no treatment administered • baseline phase—series of baseline observations • treatment observations—treatment administered • treatment phase—series of treatment observations

26. reversal design • also called ABAB design • behavior is observed during • baseline phase (A) • treatment phase (B) • baseline phase (A) • treatment phase (B)

27. reversal design A B A B

28. multiple baseline designs • reversal designs may not work • need to show treatment is effective across circumstances • multiple baseline across • subjects • behaviors • situations

30. single-subject designs • advantages • establish cause-effect between treatment and behavior • integrate experimental research with clinical practice • allows flexibility

31. single-subject designs • disadvantages • cause-effect established for only one person • needs multiple observations • no statistical control

32. feedback • thinking about my 2 lectures… • please write down 1 thing you liked • please write down 1 thing that you didn’t like/need to improve • turn it in on the table along with Rating Sheet #1