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Unformatted text preview: Hypothesis Tests for  Unknown In the last section, we learned how to perform hypothesis tests for the popu lation mean when the population standard deviation is a known value. Now, we show how to perform hypothesis tests when the population standard de viation is not known. We use the sample standard deviation s to estimate the population stan dard deviation . The test statistic is now t = x s/ n The distribution of the test statistic now follows a t distribution with ( n 1) degrees of freedom. The procedure is the same as the procedure for the known case, but pvalues and critical values are computed using the t distribution with ( n 1) degrees of freedom. 1 OneTailed Test Example : The Employment and Training Administration reported the U.S. mean unemployment insurance benefit of $238 per week. A researcher in the state of Virginia anticipated that sample data would show evidence that the mean weekly unemployment insurance benefit in Virginia was below the...
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This note was uploaded on 01/24/2011 for the course STATISTICS 19897 taught by Professor Jager,abigaill during the Fall '10 term at Kansas State University.
 Fall '10
 Jager,AbigailL
 Standard Deviation

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