CRIM 320 Lecture Notes - Lecture 7: Multiple Comparisons Problem, Standard Deviation, Confidence Interval
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8 Dec 2017
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Crim 320 module 7 analysis of variance. Anova best thought of as an extension of t-tests. Like t-tests, anova starts by comparing differences in means between groups. What happens when your grouping variable has more than two categories: > 2 groups focus on one-way anova. Within-group variability: spread around the mean (variances) Between-group variability: differences in group means. Based on these two estimates of variability, you can draw conclusions about the population means. Mean differences in means does that represent real group differences in the population. Mean first question: are there differences in means across the groups: usually there is some difference in means. Null hypothesis the population means for all groups is the same: aka: there is no differences between group mean scores on the dependent variable. Alternative hypothesis: there are differences between groups. Note: the alternative hypothesis does not state which group differences are significant: because there are more than two groups.