Comparing the output of strawberries grown on plots using fertilizer A with that grown on otherwise identical plots using fertilizer B, in order to make a general assessment of relative fertilizer effectiveness, may well call for:
A) a Friedman-Smirnov test
B) a Kruskal-Wallis test
C) a Wilcoxon rank-sum test
D) a Spearman rank correlation test
E) a chi-square test

Question

Quizplus · Accepted Answer

The Wilcoxon rank-sum test is appropriate for comparing two independent groups and assessing whether there are differences in the ranked data. In this case, we have two groups (strawberries grown with fertilizer A and with fertilizer B) and we want to compare the yields of each group. Therefore, a Wilcoxon rank-sum test would be the most appropriate choice. The other tests listed are not appropriate for this situation: the Friedman-Smirnov test is used to compare three or more related groups, the Kruskal-Wallis test is used to compare three or more independent groups, the Spearman rank correlation test assesses the relationship between two variables, and the chi-square test is used to compare observed and expected frequencies of categorical data.

Comparing the Output of Strawberries Grown on Plots Using Fertilizer