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The RANK Procedure |

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Many nonparametric methods are based on analyzing ranks of a variable:

- A two-sample
**t**-test applied to the ranks is equivalent to a Wilcoxon rank sum test using the**t**approximation for the significance level. If you apply the**t**-test to the normal scores rather than to the ranks, the test is equivalent to the van der Waerden test. If you apply the**t**-test to median scores (GROUPS=2), the test is equivalent to the median test. - A one-way analysis of variance applied to ranks is equivalent
to the Kruskal-Wallis
**k**-sample test; the F-test generated by the parametric procedure applied to the ranks is often better than the approximation used by Kruskal-Wallis. This test can be extended to other rank scores (Quade 1966). - You can obtain a Friedman's two-way analysis for block designs
by ranking within BY groups and then performing a main-effects analysis of
variance on these ranks (Conover 1980).
- You can investigate regression relationships by using rank transformations
with a method described by Iman and Conover (1979).

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