Stats 6590 Project

Body Fat Data

You have been contacted by a hospital to analyze a data set on the percentage of body fat (a measure of health) for a sample of 252 men. Body fat is estimated through an underwater weighing technique. However, your medical colleagues would like to come up with a way to estimate body fat for men using a simpler method, based on easy to obtain body measurements and information. The variables that are available to you are described below. The data file can be accessed through our course webpage:

http://www.math.mun.ca/~sneddon/st6590

If you plan on using Splus to do your data analysis, you can access the data by typing:

 attach("/users/math/faculty/sneddon/DATA")

The data is in contained in bodyfat.dat

Your goal is to develop a model that estimates the percentage of body fat from some of the available explanatory variables (Are there some variables that it would be inappropriate for you to use in your model?). Since there are 2 measures of body fat provided, you can begin by working with either of the 2 measures in developing your model.

In developing your model, watch out for any unusual cases that may exist in the data.

Data Description:

The columns of the dataset contain the following variables. Each row corresponds to a different subject:

1. Case Number
2. Percent body fat using Brozek's equation, $457/Density - 414.2$
3. Percent body fat using Siri's equation, $495/Density - 450$
4. Density ($gm/cm^3$)
5. Age (yrs)
6. Weight (lbs)
7. Height (inches)
8. Adiposity index = $\mbox{Weight}/\mbox{Height}^2 \hspace{.05in} (kg/m^2)$. This is often called the body mass index (BMI).
9. Fat Free Weight = (1 - fraction of body fat) $\times$ Weight, using Brozek's formula (lbs)
10. Neck circumference (cm)
11. Chest circumference (cm)
12. Abdomen circumference (cm) ``at the umbilicus and level with the iliac crest"
13. Hip circumference (cm)
14. Thigh circumference (cm)
15. Knee circumference (cm)
16. Ankle circumference (cm)
17. Extended biceps circumference (cm)
18. Forearm circumference (cm)
19. Wrist circumference (cm) ``distal to the styloid processes"