STA 3024 Ch 12 solutions

STA 3024 Ch 12 solutions - Solutions to even numbered...

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Solutions to even numbered problems in the suggested homeworks : Chapter 12 12.12a. Since the correlation coefficient of height (with weight) is highest compared to that between (%BF, weight) and (age, weight), we conclude that height is the best predictor of weight. Here we can directly compare the correlations because r (correlation coefficient) doesnot depend on units. b. This is because, if we add a new explanatory variable to a regression, the R 2 value either gets larger or at worst, stays the same (if the new explanatory variable is useless). c. No, age doesnot help us in predicting weight because on adding it, R 2 increases by only 1%(66% to 67%) (i.e the prediction error decreases by only 1%) which is negligible. 12.22a. The steps for the significance test are as follows : 1. Assumptions : Please see my notes. Is the sample random or convenience ? 2. Hypotheses : H 0 : β 2 = 0 vs H a : β 2 6 = 0 3. Test Statistic : t = 1.39 4. P - value : 0.17 5. Conclusion: If the null hypotheses were true, the probability would have been 0.17 of getting a
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This note was uploaded on 12/15/2011 for the course STA 3024 taught by Professor Ta during the Spring '08 term at University of Florida.

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STA 3024 Ch 12 solutions - Solutions to even numbered...

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