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Unformatted text preview: but with a .47 risk of a false alarm/Type I error. Alpha levels Monday, October 10, 2011 Power and Sample size • The actual amount of power in a study depends on where the H1 distribution is actually located: Monday, October 10, 2011 Null Hypothesis True Null false/Alternative Hypothesis True Reject H0 Fail to Reject H0 Critical Value Monday, October 10, 2011 7 Type II error is more likely Type I error risk is still equal to alpha Here, betweengroups variability in the population is small, so the effect size is relatively small. Smaller effect size means less POWER. Monday, October 10, 2011 Power and Sample Size Handout • Two usages: –(1) Estimate the power in an already completed analysis • “adequate” power is considered .80 –(2) Plan an appropriate N, given effect size estimate from prior research 8 Monday, October 10, 2011...
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This note was uploaded on 10/26/2011 for the course SLL 330 taught by Professor Damare during the Spring '10 term at USC.
 Spring '10
 DAMARE

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