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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 Ftest of β 1 = 0 versus β 1 6 = 0. The Pvalue 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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This note was uploaded on 10/04/2010 for the course STAT ST3131 taught by Professor Xiayingcun during the Fall '09 term at National University of Singapore.
 Fall '09
 XIAYingcun
 Regression Analysis

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