Prediction interval for 9000 steps per day. Let’s find the prediction interval for a future observation of BMI for a college-aged woman who averages 9000 steps per day. The predicted value is the same as the estimate of the average BMI that we calculated in Example 10.8, that is, 23.7 kg/m2. Software tells us that the 95% prediction interval is 16.4 to 31.0 kg/m2. This interval is extremely wide, covering BMI values that are classified as underweight and obese. Because of the large amount of scatter about the regression line, prediction intervals here are relatively useless.