PSY 3213L Lecture Notes - Lecture 8: Confounding, Internal Validity

• School: University of Florida
• Department: Psychology
• Course: PSY 3213L
• Professor: Melissa Cervantez

Document Summary

Introduce the iv: measure effect of iv on dv, pretest-posttest design, allows to compare the before and after effect, confirm if groups were equivalent, when to use pretest. If you have a large enough sample your randomization should make your groups equivalent though. The dropout factor in experiments is called attrition or mortality: one disadvantage of a pretest, however, is that it may be time-consuming and awkward to administer in the context of the particular experimental procedures being used. Perhaps most important, a pretest can sensitize participants to what one is studying, enabling them to figure out what is being studied and potentially why. It is also possible to assess the impact of the pretest directly with a combination of both the posttest-only and the pretest-posttest design. In this design, half the participants receive only the posttest, and the other half receive both the pretest and the posttest.