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Unformatted text preview: Review: Statistical Power Hypothesis testing with the ttest A new type of t http://www.stat.sc.edu/%7eogden/javahtml/ power/power.html z = M M t = M s M z = M 2 n t = M s 2 n Sample variance Population variance testStatistic = Difference between data and hypothesis standard distance expected by chance M = n = 2 n sample variance = s 2 = SS n 1 = SS df M s = s 2 n Estimated standard error ttest population variance not known ztest population variance known 1.State the hypothesis (null and alternative) 2.Set the decision criterion Locate the critical t for the speci f ed alpha using the appropriate df and table B.2 3.Collect sample & compute statistic compute mean, sample variance, and tstatistic 4.Compare statistic to criterion and make a decision apply same logic as with a ztest (if obtained t falls in critical region, then reject the null) 36 workers are switched to a compressed schedule (3 consecutive 13hour shifts). They rate their preference on a scale from 110 (0=prefer standard, 5=no preference, 10= prefer compressed). 1. State hypothesis H : =5 H 1 : 5 2. Set Criterion =0.05, twotailed df=n1=361=35 t critical (35)=2.031...
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This note was uploaded on 01/13/2012 for the course PSYCH 5 taught by Professor Collins during the Fall '08 term at UCSB.
 Fall '08
 COLLINS

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