Question

Berkeley Guidance Study (Data file: BGSgirls) The Berkeley Guidance Study enrolled children born in Berkeley, California, between January 1928 and Junc 1929, and then mcasured them periodically until age 18 (Tuddenham and Snyder, 1954). The data we use include heights in centi- meters at ages 2, 9, and 18, (HT2, HT9, and HT18), weights in kilogram (WT2, WT9, and WT18), leg circumference in centimeters (LG2, LG9, and LG18), and strength in kilogram (ST2, ST9, and ST18). Two additional measures of body type are also given, soma, somatotype, a scale from 1, very thin, to 7, obese, and body mass index, computed as BMI18 = WT18/ (HT18/100)?, weight in kilogram divided by the square of mass in meters, a standard measure of obesity. The data are in the files BGSgirls for girls only, BGSboys for boys only, and BGSall for boys and girls combined (in this last file an additional variable Sex has value 0 for boys and 1 for girls). For this problem use only the data on the girls." 3.3.1 For the girls only, draw the scatterplot matrix of HT2, HT9, WT2, WT9, ST9, and BMI18. Write a summary of the information in this scat- terplot matrix. Also obtain the matrix of sample correlations between the these same variables and compare with the scatterplot matrix. 3.3.2 Starting with the mean function E(BMI18|WT9) = Be + B.WT9, use added-variable plots to explore adding ST9 to get the mean function E(BMI18|WT9, ST9) = Bo + BWT 9+B_ST9. Obtain the marginal plots of BMI18 versus each of WT9 and ST9, the plot of st9 versus WT9, and then the added-variable plots for ST9. Summarize your results. 3.3.3 Fit the multiple linear regression model with mean function = = E(BMI18.X)= Be + B.HT2+B2WT2+B3HT9+BAWT9+B-ST9 (3.27) Find ô and R². Compute the t-statistics to be used to test each of the B; to be 0 against two-sided alternatives. Explicitly state the hypoth- eses tested and the conclusions.

Answer 1

Berkeley Guidance Study (Data file: BGSgirls) The Berkeley Guidance Study enrolled children born in Berkeley, California, between January 1928 and Junc 1929, and then mcasured them periodically until age 18 (Tuddenham and Snyder, 1954). The data we use include heights in centi- meters at ages 2, 9, and 18, (HT2, HT9, and HT18), weights in kilogram (WT2, WT9, and WT18), leg circumference in centimeters (LG2, LG9, and LG18), and strength in kilogram (ST2, ST9, and ST18). Two additional measures of body type a