FDN 5000 Research in Education Dr. George H. Olson, Instructor

1. FDN 5000 Research in Education Dr. George H. Olson, Instructor Research Designs Descriptive Research Designs Correlation Research Designs Causal-comparative Designs Experimental Designs Non-experimental Designs Single-subject designs

2. Purposes of Research Designs • Provide guidance in conducting research • Provide guidance in interpreting research • Guidance in recognizing types of research • Guidance in recognizing potential threats to the validity of research conclusions • Help guard against threats to internal and external validity

3. Descriptive research designs • Survey research • Longitudinal research designs • Cohort designs • Quasi-cohort designs • Cross-sectional research • Case studies • Ethnographic studies

4. Correlational research designs • Objective: study the relationship between variables • Examine scatter plots (e.g., pages 223 and 225 in our text) • Compute correlation coefficients • range from -1 through 0 to +1 • do not imply causation • lack of correlation does NOT imply no causation

5. Interpreting correlations • Rules of thumb: Correlation coefficientStrength of relationship .00 to .20 negligible .24 to .40 low .40 to .60 moderate .60 to .80 substantial .80 to 1.00 high, very high

6. Causal comparative research designs • A.k.a. ex-post-facto designs • Aimed at discovering cause and effect relationships • Defined groups are compared after they have been formed • Theory plays an important role • In arguing for the cause-effect relationship • In eliminating rival explanations

7. Causal comparative designs: An example Of students receiving the This proportion is known to following grades…. drive a car to school A 8% B 23% C 43% D 77% F 96% What should the superintendent conclude?

8. Diagramming Experimental Research Designs • Symbols used: • T = treatment intervention • C = control or comparison condition (often simply no treatment) • O = observation (often some test score) • R = designates random assignment • M = designates matching

9. Examples of Research Design Diagrams (1) T O (2) O1 T O2 O1 T O2 (3) ----------------------- (No Random Assignment) O1 C O2

10. Three pre-experimental designs • Three designs frequently used in education research that… • are not sufficient for permitting strong tests of causal hypotheses • often due suggest new ideas • One-group posttest-only design • One-group pretest-posttest design • Comparison-group posttest-only design

11. One-group, posttest-only research design T O • A treatment followed by an observation • Should not be confused with the one-shot case study • Threats to internal validity: • ALL (except regression and mortality) • Threats to external validity: • ALL

12. One-group pretest-posttest research design Opre T Opost • One of the most frequently used research designs in education • Threats to internal validity: • extraneous events (history and maturation) • statistical regression • testing • experimenter and subject effects • Threats to external validity • selection and settings interactions with treatment

13. Comparison-group, posttest-only design T O -------------- C O -------------- C2 O -------------- C3 O

14. Comparison-group, posttest-only design • Threats to internal validity • Since the comparison groups are non-equivalent, the major threat is selection • Other threats include mortality, and subject and experimenter reactive effects • Threats to external validity • Selection and settings by treatment interaction

15. True experiment research designs • Randomized experiments • Result in probabilistic equivalence • Not a panacea that rules out all threats to internal validity • Does not control for experimenter and subject reactive effects. • Does not guarantee group equivalency (especially in small samples).

16. Randomized posttest comparison group design T O R: --------------- C O Note: R: means RANDOMIZATION

17. Randomized pretest-posttest control group design Opre T Opost R: --------------------------- Opre C Opost R: --------------------------- Opre C2 Opost

18. Randomized matched-group design T O M: R: --------------- C O

19. Randomized factorial designs TA1,B1 O --------------- TA1,B2 O R: --------------- TA2,B1 O --------------- TA2,B2 O

20. Factorial Design: Example Method (B)____ Word Type (A) Computer Handwriting B1B2 Easy A120 26 Hard A216 20 ____________________________

21. Quasi-experiments: Time series designs O1 O2 O3 O4 T O5 O6 O7 O8 • Pre-observations to establish a baseline • A treatment intervention • Post-observations to establish new baseline

22. Quasi-experiments: Non-equivalent control groups • In these designs, randomization is either not possible or not feasible. • Characterized by ... • using intact groups for treatment and comparison • manipulated independent variable • Often, the best we can expect from education research

23. Non-equivalent, control group, pretest-posttest design Opre T Opost ------------------------- Opre C Opost • Except for reactive effects, most threats to internal validity are controlled • Again settings and selection by treatment interactions pose threats to external validity

24. Matched comparison group, posttest design T O M: --------- C O • Validity depends upon how well matching is achieved • Potential threats to internal validity are same as those for posttest-only designs

25. Single-subject designs • Similar to time-series designs, only with a single individual • Repeated measurements over time (baselines) • Subjects serve as their own controls • Involve a manipulated independent variable (the intervention)

26. Basic single-subject designs • Reversal: A - B - A • Double reversal: A - B - A - B • Multiple baseline: A - B - A ------------------------ A - B - A ------------------------ A - B - A ------------------------ A - B - A A is a period of no treatment B is a period of treatment

27. Example of a stable baseline

28. Example of an increasing baseline

29. Non-experimental research designs • Characterized by the lack of manipulation of an independent variable • Three types of non-experimental research designs: • Causal comparative research designs • Correlational research designs • Descriptive research designs