Refer to Exercise 7.S.6. The observations (cm), in increasing order, are shown. Compare the treatments using a Wilcoxon-Mann-Whitney test at α = 0.01. Let the alternative hypothesis be that stress tends to retard growth.

Exercise 7.S.6
A plant physiologist conducted an experiment to determine whether mechanical stress can retard the growth of soybean plants. Young plants were randomly allocated to two groups of 13 plants each. Plants in one group were mechanically agitated by shaking for 20 minutes twice daily, while plants in the other group were not agitated. After 16 days of growth, the total stem length (cm) of each plant was measured, with the results given in the accompanying table.
Consider a t test to compare the treatments with the alternative hypothesis that stress tends to retard growth.

Transcribed Image Text:

ess-7 7 5 0123779706 77788900 22222233 4567 tr 2 5 1 1 2 2 3 6 1 2 4 .5 3 5 9 0 0 0 0 0 11134 Control Stress rl 13 13 y 30.59 27.78 2.13 1.73