An analysis is performed to investigate the relationship bet

An analysis is performed to investigate the relationship between cardiovascular exercise and percent body fat. The summary statistics for 20 men and 30 women are:

Variable

Men

Women

Mean

SD

Mean

SD

# hrs cardio exercise

4.7

2.2

2.5

1.4

% body fat

20.1

3.1

31.6

8.1

Answer the following questions [Hint: S_xy =-22.0704 for men and S_xy = -193.8244 for women]

a)Estimate the regression equations relating the number of hrs of exercise to percent body fat for men and women (separately).

b)What is the expected percent body fat for a male who exercised 2 hrs per week?

c)What is the expected percent body fat for a woman who does not exercise?

d)Calculate the correlation between the 2 variables for men and explain your result.

e)How much variation in the dependent variable is left unexplained by the model for men? (none, a small amount or a large amount?)

f)What is the proportion of observed variation in men? Is this an impressive result?

Solution