1. Research Design

2. “The best way to escape a problem is to solve it.” -- Brendan Francis

3. research design n a methodology –to establish a sequence for measurement, –to reduce confounds, and –to increase control n indicates the basic structure of the study

4. A research plan is n a detailed description of a proposed study designated to investigate a specific problem. (Gay, 83). n As used in research, the term “design” refers to the researcher’s plan for how to proceed.

5. We said previously the distinction between good and poor research, more often than any other factor, is the distinction between asking a good or poor research question. The success, however, is often a function of the extent to which the methods of endeavor have been subjected to quantification through the use of measurement and mathematics.

6. Measurement n systematic representation of the data by numbers n objectives –objectivity –assignment of numbers to data according to well-established rules

7. Mathematics n the systematic representation of the relationships among the measurements with mathematical expressions n a universal language that any science or technology may use with power and convenience. n the vocabulary of mathematics is –unlimited –defined with rigorous accuracy

8. Contributors to the nature of the design n nature of the hypothesis n the variables involved –constructs n constraints of the “real world”

9. Constructs n Traits such as intelligence, learning, anxiety, motivation, are not directly observable. n Referred to as constructs -- implying constructs of the scientist’s imagination n Constructs cannot be seen heard or felt. n Can only be inferred by phenomenon such as test scores, pulse rate, observed aggressive acts, etc. Best, J. & Kahn, J. (1998). Research in Education. Boston: Allyn and Bacon.

10. Constraints of the Real World: Problems in Conducting Research With Humans n No two persons are alike. n No one person is completely consistent from moment to moment. n Humans are influenced by the research process itself. n The behavioral sciences have been limited by the use of constructs. Best, J. & Kahn, J. (1998). Research in Education. Boston: Allyn and Bacon.

11. Controlling the threats of internal and external validity is the art of research design.

12. Whether conducting research or evaluating the reporting of research findings, we want to be reasonably sure of two things: n to understand what influence, if any, the independent variable has on the dependent variable, and n to feel comfortable that the experimental environment sufficiently mirrors the real world to allow for generalizability of findings.

13. Internal and External n Internal –The differences are a result of the manipulation of the independent variable. n External – The results of the study can be expected to confirmed with similar studies of other groups

14. Threats to Internal Validity -- Campbell and Stanley n h istory n m aturation n t esting n i nstrumentation n statistical r egression n differential s election of subjects n m ortality n selection-maturation i nteraction

15. Threats to External Validity n Pretest-Treatment Interactions n Multiple Treatment Interference n Selection-Treatment Interaction n Specificity of Variables n Experimenter Effects n Reactive Arrangements

16. Controlling the threats of internal and external validity is the art of research design.

17. Methods for controlling effects of variables n Hold the variable constant n Randomize the effects of the variable n Match subjects with respect to the variable n Control the variable statistically

18. Design questions n what will be done n to whom n when

19. Must perform two related functions n must provide a logical structure that enables the researcher to pinpoint the effects of the independent variable on the dependent variable and thus answer the research question n help the researcher to rule out confounds as an alternative explanation for our findings

20. One focus of control is through participation n assignment n selection

21. n random selection –selection of the entire group of participants for an experiment –Larger samples are generally better –use of a random number generator or random number table n random assignment –after participants have been selected, they can be assigned to experimental and control groups

22. Randomization n Dewey wins! n All behavioral research should use the method of randomization. n It is the most powerful technique we have for eliminating unintended participant-assignment confounds from the design of experiments. n Randomization randomizes everything.

23. Selecting participants n who n how many n how selected n how assigned to treatments

24. selection n sampling –see text procedure types –simple random sample –stratified random sample –cluster sampling –two-stage cluster sampling

25. matching n Stratified samples n Use of matched pairs n Subject participates in each phase of the experiment. (Could be source of additional threats.)

26. controlled statistically n If two variables are correlated, one can be used to predict the other: –GPA and SAT

27. Design has answered the who -- Now -- n what will be done n when

28. A Way of Looking at Design to Maximize Internal Validity n Between Subjects design n Within Subjects design

29. Between Subjects Design n separate groups of subject receive different levels of the independent variable. n to control for individual differences: –randomly assigned subjects to groups, or –match subjects characteristics in each group

30. Within Subjects Design n all subjects receive all levels of the independent variable. n to try to minimize carry over effects: –randomize the order of treatments, or –counterbalance the order of treatments. each treatment occurs in each time period of the experiment

31. Pre-experimental designs n The One Shot Case Study n The One Group Pretest-Posttest Design n The Static Group Comparison

32. Experimental n as determined by Campbell and Stanley n participants are randomly assigned to groups n there are at least two levels of the independent variable n the design can control for the major threats to internal validity n the experiment compares two alternative theoretical positions (optional)

33. Experimental Designs n the Pretest-Posttest Control Group design n the Posttest Only Control Group design n the Solomon Four Group design

34. The Solomon Four Group Design nRO1XO2nRO3OnRXO5nRO6nRO1XO2nRO3OnRXO5nRO6

35. Quasi-Experimental designs n The nonequivalent control group design n The time series design n Counterbalanced design n Factorial design

36. Descriptive Research Methods n Survey n Interview n Observational

37. Discuss n A newspaper article suggested that people who eat breakfast are healthier than those who do not. When this research was criticized, the researcher replied, “What’s the problem? All of our participants were randomly selected.” n Respond to these researchers.

38. Question 8a Explain the difference in pre-experimental, experimental and quasi- experimental research designs. Why is randomization such an important factor?

39. Question 8b Explain the Solomon Four Group Design. What are its strengths and weaknesses?