Chapter Contents |
Previous |
Next |
The FREQ Procedure |
Procedure features: |
|
Friedman's test is a nonparametric test for treatment differences in a randomized complete block design. Each block of the design may be a subject or a homogeneous group of subjects. If blocks are groups of subjects, the number of subjects in each block must equal the number of treatments. Treatments are randomly assigned to subjects within each block. If there is one subject per block, then the subjects are repeatedly measured once they are under each treatment. The order of treatments is randomized for each subject.
In this setting, Friedman's test is identical to the ANOVA (row means scores) CMH statistic when the analysis uses rank scores (SCORES=RANK). The three-way table uses subject (or subject group) as the stratifying variable, treatment as the row variable, and response as the column variable. PROC FREQ handles ties by assigning midranks to tied response values. If there are multiple subjects per treatment in each block, the ANOVA CMH statistic is a generalization of Friedman's test.
Program |
proc freq data=hypnosis; tables subject*emotion*skinresponse emotion*skinresponse /cmh2 scores=rank noprint; |
title1 'Examining the Effect of Hypnosis on Skin Potential'; run; |
Output |
Chapter Contents |
Previous |
Next |
Top of Page |
Copyright 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.