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Unformatted text preview: Review of the 4step program Statistical Power Effect Size Introduction to the Ttest 1.State the hypothesis 2.Set the decision criterion 3.Collect sample & compute statistic 4.Compare statistic to criterion and make a decision Are times to complete a 200 m sprint affected by cold temperatures? Assume that the population of 200 m sprint times has a =22 s and =5. 1. State hypothesis H : =22 H 1 : 22 2. Set Criterion =0.05, twotailed Z critical =1.96 3. Compute sample statistics A random sample of 25 runners ran in the cold and had a mean sprint time of M=25 s z = M M z = 25 22 (525 ) = + 3 1 =+ 3.0 4. Make decision The obtained z of +3.0 is more extreme than our critical z, therefore reject H0 Cold temperatures increase times in the 200 m sprint. The power of statistical test is the probably that the test will correct reject the null hypothesis Power = p(reject false H0) = 1 Why? Size of the treatment effect Alpha level 1tailed vs. 2tailed tests Sample size Need to know the sample mean (M), the population mean ( ), and the population standard deviation...
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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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