A statistician measures the difference in songbird warble variation in twenty-five mockingbirds, both before and after nutritional supplementation with Dr. Petit Oiseau's Musical Bird Seed

Question

Warble variation is determined by a cranky librarian, who characterizes the birds, before and after treatment, as one of the following "Lots of Notes There!" "Fair Variety," and "Quite The Redundant Little Song." What considerations determine choice of a test for this research? (Select all that apply.)
a. The sample size is small to moderate.
b. There is one group of birds and all receive the treatment.
c. A before-after type of design is used.
d. The independent variable is nominal level.
e. Birds are divided into two groups.
f. The dependent variable is ordinal level.
g. The dependent variable is ratio level.

Answer 1

ANS: B, C, D, F
The parametric statistics used to determine differences that are covered in this chapter are the independent samples t-test, paired or dependent samples t-test, and analysis of variance (ANOVA). If the assumptions for parametric analyses are not achieved or if study data are at the ordinal level, then the nonparametric analyses of Mann-Whitney U, Wilcoxon signed-ranks test, and Kruskal-Wallis H are appropriate techniques to use to test the researcher's hypotheses. In this study, one group is compared before and after treatment, and the dependent variable is at the ordinal level of measurement. In such an instance, a Wilcoxon signed-ranks test is appropriate. This test is useful when a paired t-test would otherwise be performed, if only the dependent variable weren't ordinal.