1. Quazi-Experimental Designs

2. Outline of Today’s Discussion 1.True Experiments 2.Quasi-experimental Designs

3. The Research Cycle Real World Research Representation Research Results Research Conclusions Abstraction Data Analysis MethodologyGeneralization

4. Part 1 True Experiments

5. Three Features of a True Experiment: 1. Manipulation of Independent Variable(s) 2. High Level of Control (Treatment & Control Conditions) 3. Random Assignment To Conditions A true experiment unambiguously demonstrates what caused an outcome.

6. True Experiments 1.Potential Pop Quiz Question: In your own words, how does the setting (lab versus field) relate to the issue of validity (internal versus external)? 2.Potential Pop Quiz Question: In your own words, how does the ‘setting’ (lab versus field) relate to the goals of research (basic versus applied)?

7. True Experiments 1.Potential Pop Quiz Question: In your own words, explain the Hawthorne effect. http://en.wikipedia.org/wiki/Hawthorne_effect 2.Potential Pop Quiz Question: In your own words, explain what is meant by the word contamination, within the context of problems of (even) true experiments.

8. True Experiments 1.Potential Pop Quiz Question: This is a 3 part question that requires some critical thinking. A) Does ‘resentment / demoralization’ tend to increase type 1 error or type 2 error? xplain. B) Does ‘rivalry’ tend to increase type 1 error or type 2 error? Explain. C) Does ‘diffusion’ tend to increase type 1 error or type 2 error? Explain.

9. Part 2 Quasi-Experimental Designs

10. “What’s wrong with this picture?” O 1 X O 2 Inspired by Campbell & Stanley (1966)

11. Quasi-Experimental Designs Would someone please walk us through this? O 1 X O 2 - - - - - - - - - - - O 1 O 2 Inspired by Campbell & Stanley (1966)

12. Quasi-Experimental Designs 1.So, we will consider three types of quasi-experimental designs. All lack the randomization (and hence the control) of a true experiment. 2.Non-equivalent control group design - a group that is “like” the treatment group, and that can be examined by a pre-test & post-test. 3.The pre-test helps to ensure at least some meaningful similarity.

13. Quazi-Experimental Designs Would someone please walk us through Langer & Rodin (1976) study with Nursing Home Residents (see PubMed)? http://www.ncbi.nlm.nih.gov/pubmed/?term=1011073

14. Quasi-Experimental Designs 1.The next quasi-experimental design is the interrupted time series design. 2.This is used when researchers have the opportunity to observe the dependent variable for considerable time periods before and after the treatment…

15. Quasi-Experimental Designs Would someone please walk us through this? Inspired by Shadish, Cook & Campbell (2002) O 1 O 2 O 3 X O 4 O 5 O 6

16. Quasi-Experimental Designs Would someone please walk us through this? Inspired by Campbell (1969)

17. Quasi-Experimental Designs 1.Finally, the two previous quasi-experimental designs can be combined into a time series with non-equivalent control group design. 2.This is used when researchers have the opportunity to observe the dependent variable for considerable time periods before and after the treatment…

18. Quasi-Experimental Designs Would someone please walk us through this? O 1 O 2 O 3 X O 4 O 5 O 6 --------------------------------------- O 1 O 2 O 3 O 4 O 5 O 6 Inspired by Shadish, Cook & Campbell (2002)

19. Quazi-Experimental Designs Can someone apply the previous idea here? From McSweeney (1978) http://www.ncbi.nlm.nih.gov/pubmed/16795584

20. Quazi-Experimental Designs Arrows indicate days w/o helicopter! From Schnelle et al., 1978 http://www.ncbi.nlm.nih.gov/pubmed/16795578

22. Campbell, D.T. & Stanley, J.C. (1966). Experimental and Quasi- Experimental designs for research. Chicago, Rand McNally. Shadish, W.R., Cook, TD., & Campbell, D.T. (2002). Experimental and quasi-experimental designs for generalized causal inference, Boston, Houghton Mifflin. Campbell, D.T. (1969). Reforms as experiments. American Psychologist, 24, 409-429.