Who burns more energy? Metabolic rate, the rate at which the body consumes energy, is important in studies of weight gain, dieting, and exercise.

Table 14.1 gives data on the lean body mass and resting metabolic rate for 12 women and 7 men who are subjects in a study of dieting. Lean body mass, given in pounds, is a person’s weight leaving out all fat. Metabolic rate is measured in calories burned per 24 hours, the same calories used to describe the energy content of foods. The researchers believe that lean body mass is an important influence on metabolic rate.

(a) Make a scatterplot of the data for the female subjects. Which is the explanatory variable?

(b) Is the association between these variables positive or negative? What is the form of the relationship? How strong is the relationship?

(c) Now add the data for the male subjects to your graph, using a different color or a different plotting symbol. Does the pattern of the relationship that you observed in

(b) hold for men also? How do the male subjects as a group differ from the female subjects as a group?

TABLE 14.1 Lean body mass and metabolic rate Subject Sex Mass (lb) Rate (cal) Subject Sex Mass (lb) Rate (cal)

1 M 136.4 1792 11 F 88.7 1189 2 M 138.4 1666 12 F 72.8 913 3 F 79.4 995 13 M 114.2 1460 4 F 120.1 1425 14 F 93.3 1124 5 F 106.7 1396 15 F 75.9 1052 6 F 92.4 1418 16 F 112.4 1347 7 M 104.3 1362 17 F 90.6 1204 8 F 111.3 1502 18 M 114.1 1867 9 F 92.4 1256 19 M 103.2 1439 10 M 107.1 1614