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OverviewThe t-test is appropriate when you have a single interval dependent and a dichotomous independent, and wish to test the difference of means (for example, test mean differences between samples of men and women). The t-test may be used to compare the means of a criterion variable for two independent samples or for two dependent samples (ex., before-after studies, matched-pairs studies), or between a sample mean and a known mean (one-sample t-test). |
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Formula. Let E be the experimental condition and let C be the control condition. Let m be the means, s the standard deviations, and n be the sample size. Then
for the case of equal sample sizes, n, in both groups. See Levin (1999: 25) for the formula when sample sizes differ.