PSY 3001W Lecture Notes - Lecture 7: Tuesday Afternoon, Toothpaste, Random Assignment
Document Summary
Consequences of bad comparison groups, confounds are factors that vary systematically with the iv (and thus provide alternative explanations for the results). Not simply anything in the design that varies: identify. Whether the confounds provide plausible alternative explanations. How to design the study to remove the confounds: examples, petunia wants to determine which of two types of plant food is most effective. She puts bob"s big blooms on half of her geraniums and places them on her deck. She puts fern"s fabulous flowers on the other half and places them in the bay window of her kitchen. She then waits 2 weeks and measures the size of each of the flowers. Confound: location of flowers, deck, kitchen, etc. Fix: place all in the same area, or half in each location, dr. fairchild would like to study whether people who have visible tattoos are treated differently than those without tattoos.
