EXAMPLE 2.23

Check the calculations. Verify from the data in Example 2.19 that the mean and standard deviation of the 16 increases in NEA are

The mean and standard deviation of the 16 fat gains are

The correlation between fat gain and NEA increase is r = −0.7786. Therefore, the least-squares regression line of fat gain y on NEA increase x has slope

and intercept

The equation of the least-squares line is

When doing calculations like this by hand, you may need to carry extra decimal places in the preliminary calculations to get accurate values of the slope and intercept. Using software or a calculator with a regression function eliminates this worry.