statsstudy - Instructor: Julia Simms TR 2-3:15 Peck Hall...

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Instructor: Julia Simms TR 2-3:15 Peck Hall 3303 STUDY GUIDE CHAPTERS 5-9 CHAPTER FIVE Definitions: Response variable: measures an outcome or result of a study Explanatory variable: variable that we think explains or causes changes in the response variables Subjects: individuals studied in an experiment Treatment: any specific experimental condition applied to the subjects Lurking variable: has an important effect on the relationship among the variables in a study but is not one of the explanatory variables studied Confounding: happens when the effects of two variables on a response variable cannot be distinguished from each other Confounded variables can be explanatory or lurking variables. Clinical trials: experiments that study he effectiveness of medical treatments on actual patients Placebo: dummy treatment with no active ingredients Randomized comparative experiment: Random assignment One group for each treatment Number of subjects in each group What treatment each group gets Response variable we compare Control group: comparing the treatment and control groups allows us to control the effects of lurking variables The logic of experimental design:
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Randomization produces groups of subjects that should be similar in all respects before we apply the treatments Comparative design ensures that influences other than the experimental treatments operate equally on all groups Therefore, differences in the response variable must be due to the effects of the treatments Control the effects of lurking variables on the response by comparing two or more treatments Randomize -- use impersonal chance to assign subjects to treatments Use enough subjects in each group to reduce variation in the results Statistically significant: an observed effect so large that it would rarely occur by chance Good studies are comparative even when they are not experiments; a good comparative study measures and adjusts for confounding variables.
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statsstudy - Instructor: Julia Simms TR 2-3:15 Peck Hall...

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