18 experimental and quasi-experimental research


Published on

  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

18 experimental and quasi-experimental research

  1. 1. Experimental and QuasiExperimental Research KNES 510 Research Methods in Kinesiology 1
  2. 2. Experimental Research Tries to Establish Cause and Effect Selection of a good theoretical framework Application of appropriate experimental design Use of correct statistical model and analysis Proper selection and control of independent variables Appropriate selection and measurement of dependent variables Correct interpretation of results 2
  3. 3. Three Criteria for Cause and Effect 1. The cause must precede the effect in time 2. The cause and effect must be correlated with each other 3. The correlation between cause and effect cannot be explained by another variable 3
  4. 4. Reviewing Important Terms Independent variable Dependent variable Categorical variable-(age, sex=not controlled) Control variable-exclude Extraneous variable 4
  5. 5. Types of Validity Internal validity External validity Trade-off between internal and external validity Series of experiments (studies) 5
  6. 6. Threats to Internal Validity History-during Maturation Testing Instrumentation Statistical regression Selection bias 6
  7. 7. Threats to Internal Validity, cont’d Experimental mortality Selection-maturation interaction Expectancy 7
  8. 8. Threats to External Validity Reactive or interactive effects of testing Interaction of selection biases and treatment Reactive effects of experimental arrangements Multiple-treatment interference 8
  9. 9. Controlling Threats to Internal Validity Randomization – Real randomization – Matched pairs (but not matched groups) – Randomizing treatments or counterbalancing Placebos Blind setups Double-blind setups 9
  10. 10. Uncontrolled Threats to Internal Validity Reactive effects of testing Instrumentation Experimental mortality 10
  11. 11. Controlling Threats to External Validity Selecting from larger population – Participants – Treatments – Situations Ecological validity-emulates the real world? 11
  12. 12. Types of Designs: Pre-experimental Designs (invalid) One-shot studies T O One-group pretest-posttest O1 T O2 Statistical analysis? Dt Static group comparison (one shot w/2 groups) T O1 --------------Statistical analysis? It O 12
  13. 13. Types of Designs: True Experimental Designs Randomized-groups design R T O1 Statistical analysis? It R O2 Extending the levels—randomized-groups design R T1 O 1 Statistical analysis? Ab R T2 O 2 R O3 13
  14. 14. Types of Designs: True Experimental Designs, cont’d -1 interaction -2 main effects 14
  15. 15. Types of Designs: True Experimental Designs, cont’d A factorial design with a categorical factor (B) R A1 O1 B1 R A2 O2 R A3 O3 Statistical analysis? M ---------------------------R A1 O4 B2 R A2 O5 R A3 O6 15
  16. 16. Types of Designs: True Experimental Designs Pretest-posttest randomized-groups R O1 T O2 R O3 O4 Statistical analysis? MFA Extending the design on the RM factor R O1 T O2 T O3 Statistical analysis? MFA-RM R O4 O5 O6 16
  17. 17. Types of Designs: True Experimental Designs, cont’d Extending the pretest-posttest randomized groups design on both factors R O 1 T1 O 2 T1 O 3 R O4 R O7 T2 O5 O8 T2 O6 O9 Statistical analysis? AN (covariate) 17
  18. 18. Types of Designs: True Experimental Designs, cont’d Solomon four-group design—purpose=pretest effects R O1 T O2 R O3 O4 R T O5 R O6 Statistical analysis (factorial ANOVA) No treatment Treatment Pretested O4 O2 Unpretested O6 O5 18
  19. 19. Quasi-Experimental Designs: Time Series (slope) D.T. Campbell and J.C. Stanley, Experimental and quasi-experimental designs for research. Copyright © 1963 by Houghton Mifflin Company. Reprinted with permission. 19
  20. 20. Quasi-Experimental Designs: Reversal (return to baseline) 20
  21. 21. Quasi-Experimental Designs: Ex Post Facto (discriminate) This is one of the pre-experimental designs, but with the treatment not under the control of the experimenter. T O1 ------------------ Statistical analysis? A O2 21
  22. 22. Quasi-Experimental Designs: Switched Replication Levels 1 1 O1 T Trials 2 3 O2 O3 4 O4 5 O5 2 O6 O7 O9 O10 3 O11 O12 O13 T O14 O15 4 O16 O17 O18 T O8 O19 T O20 22
  23. 23. Quasi-Experimental Designs: Single Participant Identify participant and follow over time. Does the treatment produce the same effect each time? Are treatment effects cumulative, or does participant return to baseline? Does participant’s response become less variable over treatment times? 23
  24. 24. Quasi-Experimental Designs: Single Participant, cont’d Is participant’s magnitude of response sensitive to multiple treatment applications? Do varying intensities, frequencies, and lengths of treatment produce varying responses? 24
  25. 25. Next Class Chapter 15 Abstracts tonight Research Q? 3 intro paragraphs 1. 2. 3. Rationale Lit summary Empty space and purpose 25