Exact Wilcoxon signed-rank and Wilcoxon Mann-Whitney ranksum tests
Tammy Harris
Institute for Families in Society
Department of Epidemiology & Biostatistics
University of South Carolina
Columbia, SC
[email protected]
|
James W. Hardin
Institute for Families in Society
Department of Epidemiology & Biostatistics
University of South Carolina
Columbia, SC
[email protected]
|
Abstract. We present new Stata commands for carrying out exact Wilcoxon one-sample and
two-sample comparisons of the median. Nonparametric tests are often used in
clinical trials, in which it is not uncommon to have small samples. In such
situations, researchers are accustomed to making inferences by using exact
statistics. The ranksum and signrank commands in Stata provide
only asymptotic results, which assume normality. Because large-sample results
are unacceptable in many clinical trials studies, these researchers must use
other software packages. To address this, we have developed new commands for
Stata that provide exact statistics in small samples. Additionally, when
samples are large, we provide results based on the Student’s t
distribution that outperform those based on the normal distribution.
View all articles by these authors:
Tammy Harris, James W. Hardin
View all articles with these keywords:
ranksumex, signrankex, exact distributions, nonparametric tests, median, Wilcoxon matched-pairs signed-rank test, Wilcoxon ranksum test
Download citation: BibTeX RIS
Download citation and abstract: BibTeX RIS
|
