Chapter_13_-_Recommended_Problems_-_Answers

Chapter_13_-_Recommended_Problems_-_Answers - 13.3 (a) (b)...

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13.3 (a) When X = 0, the estimated expected value of Y is 16. (b) For each increase in the value X by 1 unit, you can expect a decrease in an estimated 0.5 units in the value of Y . (c) 13 ˆ Y 13.13 r 2 = 0.75. So, 75% of the variation in the dependent variable can be explained by the variation in the independent variable. 13.15 Since SST = SSR + SSE and since SSE cannot be a negative number, SST must be at least as large as SSR . 13.17 (a) r 2 = 0.9015. So, 90.15% of the variation in audit newsstand sales can be explained by the variation in reported newsstand sales. (b) 42.1859 YX S (c) Based on (a) and (b), the model should be very useful for predicting audited sales. 13.35 (a) b 0 = 169.455, b 1 = 1.8579 (b) Y ˆ = 76.56 (c) No need to worry about plotting residuals because you won t be asked to do that in the exam. (d) The Durbin-Watson test statistic of 1.18<1.27. There is evidence of positive autocorrelation among the residuals. (e) The plot of the residuals versus temperature indicates that positive residuals tend to occur for the lowest
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