PSYB07H3 Study Guide - Final Guide: Mean Absolute Difference
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If is known and 2 is unknown, we must estimate 2 with s2 i. e. if you don"t know the population variance use the sample variance to estimate. Because we use s, we can no longer declare the answer to be a z but rather it is a t. T table has critical values instead of t-values. Differences in formulas: m z x s m x s. N vs. (substitute s2 for 2) t x. To treat t as a z would give us too many significant results x x m. Therefore, for the student"s t distribution, we switch to the t-table when we use s2. For one-sample cases, degrees of freedom: df = n-1 for sample but if given , no need for n-1 just n. 1 df is lost because we used (sample mean) to calculate s2. (x-) = 0, all x can vary save for 1. Last 100 years: = 76. 0 (no tutorials)
