COMM 1 Lecture Notes - Lecture 11: Regression Analysis, Blind Experiment, Random Assignment
19 Oct 2020
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Effects related to pre-testing testing/sensitization effect: gives you an idea of what the study is about. The fact that they are thinking about it may affect their attitudes and change them since they are brought to attention. E. g. , reading scores in children from beginning to end of year. Mortality (attrition): people dropping out of your study because it becomes too involved for them. Again, random assignment to proper conditions (treat everyone the same)! Selection bias: something to do with the people themselves, and not your procedure. Could be a special group of people, an existing classroom, not randomly assigned or different. Usually a problem if you don"t have two groups or random assignment. History effect: any time something outside of the context of your study or in participants sphere of experience. Statistical regression (to the mean): rare, but still need to watch out for it. Laws of chance on repeated trials always go toward the mean.
