User Guide

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Chapter 34
If your data are continuous, use the sign test or the Wilcoxon signed-rank test.
The sign test computes the differences between the two variables for all cases and
classifies
the differences as either positive, negative, or tied. If the two variables are
similarly distributed, the number of positive and negative differences will not differ
significantly. The Wilcoxon signed-rank test considers information about both the
sign of the
differences and the magnitude of the differences between pairs. Because
the Wilcoxon signed-rank test incorporates more information about the data, it is
more powerful than the sign test.
If your dat
a are binary, use the McNemar test. This test is typically used in a
repeated measures situation, in which each subject’s response is elicited twice, once
before and once after a specified event occurs. The McNemar test determines whether
the initi
al response rate (before the event) equals the final response rate (after the
event). This test is useful for detecting changes in responses due to experimental
intervention in before-and-after designs.
If your da
ta are categorical, use the marginal homogeneity test.Thisisan
extension of the McNemar test from binary response to multinomial response. It tests
for changes in response using the chi-square distribution and is useful for detecting
respons
e changes due to experimental intervention in before-and-after designs. The
marginal homogeneity test is available only if you have installed Exact Tests.
Two-Rel
ated-Samples Tests Options
Figure 34-19
Two-Related-Samples Options dialog box
Statistics. You can choose one or both of the following summary statistics:
 Descriptive. Displays the mean, standard deviation, minimum, maximum, and the
number of nonmissing cases.
 Quartiles. Displays values corresponding to the 25th, 50th, and 75th percentiles.