Chapter 8, Problem 131P

Cigarette smoking has important health consequences and is positively associated with heart and lung diseases. Less well known are the consequences of quitting smoking. A group of 10 nurses, from the Nurses’ Health Study, ages 50−54 years, had smoked at least 1 pack per day and quit for at least 6 years. The nurses reported their weight before and 6 years after quitting smoking. A commonly used measure of obesity that takes height and weight into account is BMI = wt/ht2 (in units of kg/m2). The BMI of the 10 women before and 6 years after quitting smoking are given in the last 2 columns of Table 8.32.

Table 8.32 BMI change in 50- to 54-year-old women over a 6-year period

What test can be used to assess whether the mean change in BMI over 6 years is different between women who quit smoking and women who have never smoked?