COMM 88 Lecture Notes - Lecture 14: Caffeine
Document Summary
Compares participant groups and measures the degree of change occurring as a result of treatments or interventions. If you get a difference between group means (on y2), then the iv caused it. Possible problem: differents in y2 might be result of interaction of manipulation with pretest. Y2 difference may not just be because of x differences, but could be because of how x differences interact with y1. Solomon 4-group design: to see if pre-testing is influencing the post-test results. Pros: powerful, yields a lot of information about pre-test influencing. To check on the random assignments and outside influences. So it"s expensive if it"s used just for that purpose. It"s not a good idea to use if treatment/pre-test interaction is likely. Purpose: to examine the effects of two or more iv"s simultaneously. Each factor/iv has at least two levels (conditions) Two factors create multiple combinations of iv"s. Factorial designs test for two kinds of effects:
