A buyer for a manufacturing plant suspects that his primary supplier of raw materials is overcharging. In order to determine if his suspicion is correct, he contacts a second supplier and asks for the prices on various identical materials. He wants to compare these prices with those of his primary supplier. He collected data on 6 different materials from both suppliers. He believes that the differences are normally distributed. Which of the following tests will be the most appropriate?
A) Pooled-variance t test
B) Paired t test
C) Wilcoxon rank sum test
D) McNemar test

Question

Quizplus · Accepted Answer

Since the buyer has collected prices for identical materials from both suppliers, it is reasonable to assume that these prices are paired. Therefore, a paired t test is the most appropriate test to compare the means of the paired differences. A pooled-variance t test assumes that the variances of the two groups are equal, which may not be the case here. The Wilcoxon rank sum test is a non-parametric test and is not suitable for paired data. The McNemar test is used to compare paired proportions and is not applicable here.

A Buyer for a Manufacturing Plant Suspects That His Primary