Determine the sample correlation coefficients of (1) age with dry weight and (2) age with log10(dry weight). Which pair has stronger association? For each of them, test whether , and interpret your results.
Use SAS to do the following analysis and answer questions. Dataset “ch05q01.txt” is in the Data folder, where ‘DRYWT’ and ‘LOGDRYWG’ represent dry weight and log10(dry weight), respectively.
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Determine the sample correlation coefficients of (1) age with dry weight and (2) age with log10(dry weight). Which pair has stronger association? For each of them, test whether , and interpret your results.
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Using Fisher’s Z transformation, obtain a 95% CI for between (1) age and dry weight, (2) age with log10(dry weight).
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Fit two regression lines: (1) dry weight on age, (2) log10(dry weight) on age. Write down the fitted regression lines.
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For each model in (c), get the residual plots and comment on whether the assumptions of straight line regression are satisfied. Does the log transformation of dry weight improve the model fitting?
SAMPLE ASSIGNMENT
