We want to predict percent body fat using the measurement for neck circumference.
(a) Use the bodyfat data set to build a simple linear regression model for percent body fat (siri), where
neck circumference (neck) is the predictor. In this data set, neck is measured in centimeters.
(b) What is the expected (mean) increase in the percent body fat corresponding to one unit increase in neck circumference.
(c) Create a new variable, neck.in, whose values are neck circumference in inches. Rebuild the regression model for percent body fat using neck.in as the predictor.
(d) What is the expected (mean) increase in the percent body fat for one unit (1 inch=2.54 centimeter) increase in neck.in.
(e) Compare the estimates of regression coefficient t obs values and R2 values between the two models.
