A supermarket chain assigns 15 stores to Display Type A and 15 stores to Display Type B and records items sold per store. Which test compares the mean sales between the two independent display methods?

A supermarket chain assigns 15 stores to Display Type A and 15 stores to Display Type B and records items sold per store. Which test compares the mean sales between the two independent display methods?

• A. Paired t-test
• B. 2-sample t-test
• C. ANOVA
• D. Mann-Whitney U test

Answer: (B)

Two independent samples are being compared to see if their means differ. With 15 stores using Display Type A and 15 stores using Display Type B, you have two separate groups of sales data. The test that assesses whether the average sales differ between these two independent groups is the two-sample t-test. It checks if the difference in means is statistically significant, assuming the data are roughly normally distributed (or using Welch’s version if variances differ). A paired t-test would apply only if the same stores were measured under both displays, which isn’t the case here. ANOVA is used when comparing means across three or more groups (or multiple factors); with only two groups, a t-test directly compares the means. The Mann-Whitney U test is a nonparametric alternative that compares distributions rather than means and is used when normality isn’t assumed; however, since the goal is to compare means, the two-sample t-test is the most appropriate choice.

Two independent samples are being compared to see if their means differ. With 15 stores using Display Type A and 15 stores using Display Type B, you have two separate groups of sales data. The test that assesses whether the average sales differ between these two independent groups is the two-sample t-test. It checks if the difference in means is statistically significant, assuming the data are roughly normally distributed (or using Welch’s version if variances differ). A paired t-test would apply only if the same stores were measured under both displays, which isn’t the case here. ANOVA is used when comparing means across three or more groups (or multiple factors); with only two groups, a t-test directly compares the means. The Mann-Whitney U test is a nonparametric alternative that compares distributions rather than means and is used when normality isn’t assumed; however, since the goal is to compare means, the two-sample t-test is the most appropriate choice.