# Question

In Exercise 8.2-13, data are given that show the effect of a certain fertilizer on plant growth. The growths of the plants in mm over six weeks are repeated here, where Group A received fertilizer and Group B did not:

We shall test the hypothesis that fertilizer enhanced the growth of the plants.

(a) Construct a back-to-back stem-and-leaf display in which the stems are put down the center of the diagram and the Group A leaves go to the left while the Group B leaves go to the right.

(b) Calculate the value of the Wilcoxon statistic and give your conclusion.

(c) How does this result compare with that using the t test in Exercise 8.2-13?

We shall test the hypothesis that fertilizer enhanced the growth of the plants.

(a) Construct a back-to-back stem-and-leaf display in which the stems are put down the center of the diagram and the Group A leaves go to the left while the Group B leaves go to the right.

(b) Calculate the value of the Wilcoxon statistic and give your conclusion.

(c) How does this result compare with that using the t test in Exercise 8.2-13?

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