The first step in a Wilcoxon rank sum test is to combine the data values in the two samples and assign a rank of 1 to the:
a. smallest observation
b. middle observation
c. largest observation
d. observation that occurs most frequently
e. observation that occurs least frequently
Q. 2Consider the following data set: 2.2, 2.3, 2.3, 2.5, 2.6, 2.7, 2.8, 2.8, 2.8, 2.9, 3.1, 3.2, and 3.5 . The rank assigned to the three observations of value 2.8 is:
a. 6
b. 7
c. 8
d. 9
e. 10
Q. 3A nonparametric method that is equivalent to the Wilcoxon rank sum test is the:
a. Wilcoxon signed rank sum test
b. Friedman test
c. Kruskal-Wallis test
d. Mann-Whitney test
e. chi-square test
Q. 4Which of the following will never be a required condition of a nonparametric test?
a. The samples are drawn from normally distributed populations.
b. The samples are drawn from abnormally distributed populations.
c. The populations being compared are identical in spread and shape.
d. Both the samples are drawn from normally distributed populations and the samples are drawn from abnormally distributed populations.
e. Neither the samples are drawn from normally distributed populations nor the samples are drawn from abnormally distributed populations.
Q. 5In a normal approximation to the Wilcoxon rank sum test, the standardized test statistic is calculated as z = 1.80 . For a two-tail test, the p-value is:
a. 0.0359
b. 0.4641
c. 0.2321
d. 0.0718
e. 0.0528
Q. 6You are performing the Wilcoxon rank-sum test. The 13th through 15th values in an ordered array of pooled sample data all equal 180 (while the 12th value is less and the 16th value is more). The appropriate ranks for the three 180 values are:
a. 13, 14, 15
b. 14, 14, 14
c. 12.5, 13, 14.5
d. 12.5, 13, 15
e. 13, 13, 13
Q. 7A Wilcoxon rank sum test for comparing two populations involves two independent samples of sizes 15 and 20 . The un-standardized test statistic (that is the rank sum) is T = 210 . The value of the standardized test statistic z is:
a. 14.0
b. 10.5
c. 6.0
d. -2.0
e. -3.2
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