Question

II.16. Slope. The line on the scatter-plot in Figure II.3 is the least-squares regression line for predicting brain weight from body weight. The slope of this line is one of the numbers below. Which number is the slope? Why?

  1. (a) b = 0.5.

  2. (b) b = 1.3.

  3. (c) b = 3.2.

From Rex Boggs in Australia comes an unusual data set: before showering in the morning, he weighed the bar of soap in his shower stall. The weight goes down as the soap is used. The data appear in Table II.3 (weights in grams). Notice that Mr. Boggs forgot to weigh the soap on some days. Exercises II.17, II.18, and II.19 are based on the soap data set.

TABLE II.3 Weight (grams) of a bar of soap used to shower
Day Weight Day Weight Day Weight
1 124 8 84 16 27
2 121 9 78 18 16
5 103 10 71 19 12
6 96 12 58 20 8
7 90 13 50 21 6
Source: Rex Boggs.