PSYC 201 Lecture Notes - Time Series, Psych, Factorial Experiment
17 Dec 2013
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Main effect with variable one, add both and divide by two to get the mean and compare to other variable. Quiz: b (there can be no main effect of a and b but there is an axb interaction) Example: cross-over interaction (each mean of each variable are equal: c, c (simple effects test is done to analyze data from factorial design that yields a significant interaction) Ex post facto (after the fact) studies are particularly weak (e. g. i use pantene and my hair is great!) Adding a control (comparison) condition of some kind can increase internal validity. If possible, collect dv before as well as after. Ideally, have both comparison group and before/after (better yet, Repeated treatment designs equivalent to interrupted time series designs except that there are two or more periods during which treatment is delivered. Ideally the timing of the treatment periods is random.
