PSY 241 Lecture Notes - Lecture 15: Repeated Measures Design

• School: University of Maine
• Department: Psychology
• Course: PSY 241
• Professor: Peter Dearborn

Document Summary

Independent measures: compares two different samples of participants, uses a separate sample for each treatment condition, between subjects design. Related samples: measures the same sample of participants twice, or compares two carefully matched samples, within subjects design. Uses difference scores instead of raw scores. Different scores: scores obtained after treatment minus scores obtained before treatment. D scores tell you the direction of change. Repeated measures: same sample is measured more than once. Matched subjects: each individual in one sample is matched with an individual in the 2nd sample. Calculating differences scores turns two sample problem into one sample problem. Now more similar to one sample t test than an independent samples t test. Two different samples matched on a particular variable. Used when it would be problematic to use data from the same sample. Related samples: need fewer subjects, reduces problems caused by individual differences, best for studying changes over time. Problems that can arise in repeated measures designs.