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Unformatted text preview: TUTORIAL 3 1. Refer to the Grade point average problem (see tutorial 1) (a) obtain a 95% percent interval estimate of the mean freshman GPA for students whose ACT test score is 28. Interpret your confidence interval. (b) Mary Jones obtained a score of 28 on the entrance test. Predict her freshman GPA using a 95% prediction interval. Interpret your prediction interval. (c) Is the prediction interval in part (b) wider than the confidence interval in part (a)? Should it be. 2. Refer to the Airfreight breakage problem (see tutorial 2) (a) When X = 2 and 4, find 99% confidence intervals for each of X , interpret your results (b) with X = 2 find the 99% prediction interval. interpret your interval 3. An analyst fitted normal error regression model and conducted an F-test of β 1 = 0 versus β 1 6 = 0. The P-value of the test was 0.033 and the analyst concluded H a : β 1 6 = 0. Was the α level used by the analyst greater than or smaller than 0.033? If the α level had been 0.01, what would be the appropriate conclusion?level had been 0....
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- Fall '09
- Regression Analysis