Consumers were asked to "rate" the taste of three popular brands of yogurt that have been modified to include fibre. The data are shown in the table below. Are there differences in the results among the three brands?
a. What nonparametric method is appropriate for analyzing these data?
b. State the null and alternative hypotheses.
c. Perform the test and state your conclusion at α = 0.05.
d. If these data did satisfy the assumptions for performing ANOVA, what are the disadvantages of using this nonparametric method instead?

Question

Consumers were asked to "rate" the taste of three popular brands of yogurt that have been modified to include fibre. The data are shown in the table below. Are there differences in the results among the three brands?
  a. What nonparametric method is appropriate for analyzing these data?
b. State the null and alternative hypotheses.
c. Perform the test and state your conclusion at α = 0.05.
d. If these data did satisfy the assumptions for performing ANOVA, what are the disadvantages of using this nonparametric method instead?

Quizplus · Accepted Answer

The Answer is a. Kruskal-Wallis Test
b. H0: All three brands have the same distribution of customer rating.
HA: At least one brand has a different distribution from the others.
c.

H = 8.345. Critical χ2 = 5.991. Therefore we reject the null hypothesis and conclude that at least one brand has a different distribution from the others.
d. ANOVA would be more powerful. Using the Kruskal-Wallis instead of ANOVA, when the assumptions for the latter are satisfied, decreases the power of the test.

Consumers Were Asked to "Rate" the Taste of Three Popular