EXAMPLE 2.26

Residuals for fat gain. Example 2.19 (page 107) describes measurements on 16 young people who volunteered to overeat for eight weeks. Those whose nonexercise activity (NEA) spontaneously rose substantially gained less fat than others. Figure 2.23(a) is a scatterplot of these data. The pattern is linear. The least-squares line is

fat gain = 3.505 − (0.00344 × NEA increase)

One subject’s NEA rose by 135 calories. That subject gained 2.7 kilograms of fat. The predicted gain for 135 calories is

The residual for this subject is, therefore,