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Unformatted text preview: Subsequent Inferences for oneway ANOVA if the overall F test does not show significant differences among the groups, no further infer ences are required if the overall test does show a significant difference, differ ences between particular means can be tested using T = x i. x k. MSE r 1 n i + 1 n k in these expressions, MSE is the estimate of 2 , and the degrees of freedom are N a , the same as for MSE however, adjustments must be made for simultaneous in ference i.e. for the fact that several tests are being done the simplest adjustment is the Bonferroni correction , which reduces the significance level for each test so that the overall significance level is no larger than the desired level in a oneway ANOVA with a groups, there are r = a 2 natural comparisons between pairs of groups if you do r tests at level , then the probability of rejecting at least one H incorrectly could be as large as r 1 for example for r = 2 P ( reject at least one H ) = P ( reject 1 st ) + P ( reject 2 nd ) P ( reject both ) 2 to control the overall level, or experimentwise error rate , at , each test should be done using * = /r alternatively the P value should be...
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 Spring '12
 daniel

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