ST512 Lab 1 key

ST512 Lab 1 key - Does age appear to account for some of...

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Page 1 of 2 ST512 Assignment 1. KEY 1. What is the age of the youngest person in this data set? What is the age of the oldest person? Youngest: 18 years Oldest: 67 years 2. Use the simple linear regressions of weight vs. age and weight vs. height to complete the tables below. Predictor Estimated slope t-statistic p-value Age 0.288 4.761 <.0001 Height 1.018 23.14 <.0001 Predictor MSE R 2 Age 170.8 0.043 Height 86.7 0.515 3. 90% CI for 1 β : (0.945, 1.090) 4. Test H o : 1 1 = kg/cm vs. H a : 1 1 kg/cm. t = 0.401 p = 0.69 5. Does weight appear to be a linear function of height? Yes, the regression line appears to provide an adequate fit to the scatter plot of the raw data. Does the constant variance assumption appear justified? For the most part, yes – the plot of residuals vs. fitted values doesn’t show any pronounced trends in variance. Does the normality assumption appear justified? No. Curvature in the Q-Q plot suggests mild asymmetry (right-skew) in the residuals.
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Unformatted text preview: Does age appear to account for some of the unexplained variability in weight? No there is no clear trend in the plot of residuals vs. age. Page 2 of 2 6. Predicted weight for an individual who is 175 cm tall: 73.1 kg 99% prediction interval for this prediction: (49.0 kg, 97.2 kg) 7. Compare the model that used height (in cm) to predict weight (in kg) with the model that used height in inches to predict weight in pounds by filling in the following table. Predictor Response Estimated slope t-statistic p-value R 2 Height (in cm) Weight (in kg) 1.018 23.14 &lt;.0001 0.515 Height2 (in inches) Weight2 (in pounds) 5.686 23.14 &lt;.0001 0.515 8. Changing the units in which the predictor and response are measured changes the slope by the equivalent amount. However, the standard errors also change by the same amount, so the t-statistic and R-squared are unaffected. 9. a: TRUE, b: FALSE, c: FALSE, d: FALSE 10. a. TRUE, b: FALSE, c: TRUE, d: FALSE...
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This note was uploaded on 10/22/2009 for the course ST 512 taught by Professor Dickey during the Spring '07 term at N.C. State.

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ST512 Lab 1 key - Does age appear to account for some of...

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