Psychology 2810 Study Guide - Midterm Guide: Null Hypothesis, Aspirin

• School: Western University
• Department: Psychology
• Course: Psychology 2810
• Professor: Sandra Hessels

Document Summary

Within-subjects or between-subjects: performance on a memory test in 20- year-olds compared to 70-year-olds, political opinions of canadians and americans, performance on test a in the morning vs. at night, satisfaction with brands of tennis racquets. A good thing about within-subjects designs: subjects may differ in ways that affect the dependent variable (increase error value), a within-subjects design discounts the variability due to subject effects (increases power), one way- one independent variable. S k (msubject gm)^2 ; k=number of groups. Sstotal ssbetween sssubjects df formulae df total. Ngroups 1 or k - 1 df subjects n 1 (number of subject in each group = n) df within dftotal dfbetween dfsubjects or (dfbetween)(dfsubjects) Start with the null hypothesis- there is no main effect. Experimental hypothesis- there is a difference somewhere. Now calculate the means for each group. F critical - 4. 46 reject the null hypothesis signi cant main effect.