topic Re: how to get one-sided p value from wilcoxon signed rank test using proc univariate? in Statistical Procedures https://communities.sas.com/t5/Statistical-Procedures/how-to-get-one-sided-p-value-from-wilcoxon-signed-rank-test/m-p/126570#M6662 <HTML><HEAD></HEAD><BODY><P>In <EM>Common Statistical Methods for Clinical Research with SAS Examples, Third Edition</EM> (pg. 258), it states, "SAS uses the t-approximation to the Wilcoxon signed-rank test if n is greater than 20.&nbsp; For n &lt;=20, SAS computes the exact probability."&nbsp; As for getting the 1-sided p-value from a 2-sided p-value, you should be able to simply divide by 2 as you suggested.</P></BODY></HTML> Wed, 01 May 2013 14:45:49 GMT djbateman 2013-05-01T14:45:49Z how to get one-sided p value from wilcoxon signed rank test using proc univariate? https://communities.sas.com/t5/Statistical-Procedures/how-to-get-one-sided-p-value-from-wilcoxon-signed-rank-test/m-p/126569#M6661 <HTML><HEAD></HEAD><BODY><P>Proc Univariate provides two-sided p-value for wilcoxon signed rank test. If&nbsp; n&gt;20, can I divide the two-sided p-value by 2 to get one-sided p-value? Does SAS do normal approximation of signed rank statistics when n &gt; 20? Thanks.</P></BODY></HTML> Wed, 01 May 2013 14:24:57 GMT https://communities.sas.com/t5/Statistical-Procedures/how-to-get-one-sided-p-value-from-wilcoxon-signed-rank-test/m-p/126569#M6661 sky1 2013-05-01T14:24:57Z Re: how to get one-sided p value from wilcoxon signed rank test using proc univariate? https://communities.sas.com/t5/Statistical-Procedures/how-to-get-one-sided-p-value-from-wilcoxon-signed-rank-test/m-p/126570#M6662 <HTML><HEAD></HEAD><BODY><P>In <EM>Common Statistical Methods for Clinical Research with SAS Examples, Third Edition</EM> (pg. 258), it states, "SAS uses the t-approximation to the Wilcoxon signed-rank test if n is greater than 20.&nbsp; For n &lt;=20, SAS computes the exact probability."&nbsp; As for getting the 1-sided p-value from a 2-sided p-value, you should be able to simply divide by 2 as you suggested.</P></BODY></HTML> Wed, 01 May 2013 14:45:49 GMT https://communities.sas.com/t5/Statistical-Procedures/how-to-get-one-sided-p-value-from-wilcoxon-signed-rank-test/m-p/126570#M6662 djbateman 2013-05-01T14:45:49Z Re: how to get one-sided p value from wilcoxon signed rank test using proc univariate? https://communities.sas.com/t5/Statistical-Procedures/how-to-get-one-sided-p-value-from-wilcoxon-signed-rank-test/m-p/126571#M6663 <HTML><HEAD></HEAD><BODY><P>Be careful in the direction. The one-sided p-value is either P/2 <EM>or</EM> 1-(P/2), where P is the printed two-sided value. If the estimated statistic (or median, or mean, or whatever) is in the opposite direction of the alternative hypothesis, then the one-sided p-value will be a large number [1-(P/2)].</P></BODY></HTML> Wed, 01 May 2013 17:00:41 GMT https://communities.sas.com/t5/Statistical-Procedures/how-to-get-one-sided-p-value-from-wilcoxon-signed-rank-test/m-p/126571#M6663 lvm 2013-05-01T17:00:41Z