PSYC 301 Lecture Notes - Lecture 12: Total Variation, Analysis Of Variance, Theoretical Definition
20 Aug 2016
School
Department
Course
Professor
Document Summary
Chapter 12: data analysis and interpretation stage 3: confirm what the data reveal. Goal: determine whether mean differences among groups in an experiment are greater than differences expected simply because of change (error variation) Step 1: assume groups do not differ (ho) Step 2: compute appropriate statistic to test for group differences. Statistically significant: reject ho and conclude iv had an effect on dv. Difference between means is larger than what would be expected if error variation (chance) along caused the outcome. Type i error: reject ho when it is true (= alpha, level of significance) When 2 means are from different independent groups design: use independent groups t-test. When 2 means are from repeated measures design or matched groups: use within-subjects (repeated measures) t-test. Independent groups t-test: differece between 2 means (treatment, control) divided by the standard error of the mean difference. If observed p value < . 05: reject ho, conclude iv had significant effect on dv.
