EXAMPLE 10.8

Confidence interval for an average of 9000 steps per day. Let’s find the confidence interval for the average BMI at x = 9.0. Our predicted BMI is

= 29.578 − 0.655PA

= 29.578 − 0.655(9.0)

= 23.7

Software tells us that the 95% confidence interval for the mean response is 23.0 to 24.4 kg/m².