Exercise 9.11 Eighty wheat plants were grown in each of 5 different fields.

Each of 6 individuals (A, B, C, D, E, and F) were asked to pick 8 “representative”

plants in each field and measure the plants’s heights. Measurements were taken on 6 different days. The data consist of the differences between the mean height of the 8

“representative” plants and the mean of all the heights in the field on that day. Thus the data measure the bias in selecting “representative” plants. The exact design and the data are given below. Analyze the data. (Although they are barely recognizable as such, these data are from Cochran and Cox, 1957.)

Field Day 1 2 3 4 5 1 E 3.50 A 0.75 C 2.28 F 1.77 D 2.28 2 D 3.78 B 1.46 A−1.06 E 1.46 F 2.76 3 F 2.32 C 2.99 B−0.28 D 1.18 E 3.39 4 C 4.13 D 4.02 E 1.81 B 1.46 A 1.50 5 A 1.38 E 1.65 F 2.64 C 2.60 B 1.50 6 B 1.22 F 2.83 D 1.57 A−1.30 C 1.97