Prediction intervals for BMI. Figure 10.8 shows the upper and lower prediction limits, along with the data and the least-squares line. The 95% prediction limits are indicated by the dashed curves. Compare this figure with Figure 10.7, which shows the 95% confidence limits drawn to the same scale. The upper and lower limits of the prediction intervals are much farther away from the least-squares line than are the confidence limits. This results in most, but not all, of the observations in Figure 10.8 lying within the prediction bands.
FIGURE 10.8 The 95% prediction limits (dashed curves) for individual responses for the physical activity study, Example 10.9. Compare with Figure 10.7. The limits are wider because the margins of error incorporate the variability about the subpopulation means.