Chapter 14.5, Problem 1Q

The following data come from a field trial set up to assess the effects of different amounts of potash on the breaking strength of cotton fibers (28). The experiment was done in three blocks. The five treatment levels-36, 54, 72, 108, and 144 lbs of potash per acre-were assigned randomly within each block. The variable recorded was the Pressley strength index. Compare the effects of the different levels of potash applications using Friedman’s test. Let $a=\mathrm{0.05.}$

Pressley Strength Index for Cotton Fibers
Treatment (pounds of potash/acre)
		36	54	72	108	144
	1	7.62	8.14	7.76	7.17	7.46
Blocks	2	8.00	8.15	7.73	7.57	7.68
	3	7.93	7.87	7.74	7.80	7.21