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Unformatted text preview: APPM 4/5570 Solutions to Problems from Section 9.2 and 9.3 33. Since we are assuming that the true variances for both populations are equal, we will use a pooled ttest. (Since n 1 = n 2 = 64 / 2 = 32, I suppose you could forego this in favor of a z test.) The pooled variance is S 2 p = ( n 1 1) S 2 1 + ( n 2 1) S 2 2 n 1 + n 2 2 = (31)(3 . 2 2 ) + (31)(2 . 8 2 ) 62 9 . 04 Let 1 be the true mean weight loss for people on the vegan diet and let 2 be the true mean weight loss for people on the control diet. Hypotheses H : 1 2 = 1 H a : 1 2 > 1 Test Statistic: t = X 1 X 2 1 q S 2 p (1 /n 1 + 1 /n 2 ) 1 . 33 Degrees of freedom: n 1 + n 2 1 = 32 + 32 2 = 62; closest in ttable is 60. From Table A.5, we can see that the Pvalue is between 0 . 05 and 0 . 10. Since this Pvalue is greater than 0 . 05, we will fail to reject H in favor of H a at 0 . 05 level of significance. There is not significant evidence in the data to suggest that that the true average weight loss for the vegan diet exceeds that for the...
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This note was uploaded on 01/23/2011 for the course APPM 5440 at Colorado.
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