33. Body Mass Index. The body mass index (BMI) is a statistical measure of an individual's body weight, based on his or her weight and height. In the Framingham Heart Study,18 a sample of 1160 males had a mean BMI of 25.5 with a sample standard deviation of 3.3, and a sample of 1571 women had a mean BMI of 24.8 with a sample standard deviation of 4.3. Test whether the population standard deviation of the males' BMI is less than that of the females, using . Assume that the samples are independent and that the two populations are normally distributed.
10.4.33
Critical-value method: . . Reject if . . Since is ≤ 0.9009, we reject . There is evidence at the level of significance that the population standard deviation of the males' BMI is less than the population standard deviation of the females' BMI. method: . Reject if the . . Since the is ≤ 0.05, we reject . There is evidence at the level of significance that the population standard deviation of the males' BMI is less than the population standard deviation of the females' BMI.