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From |
Garry Anderson <g.anderson@unimelb.edu.au> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: RE: Two-sided P value for Wilcoxon (Mann-Whitney) rank-sum test |

Date |
Fri, 03 Oct 2008 00:39:17 +1000 |

Hi Andres, The z=0.385 and p=0.700 suggests that this is a two-sided test. A z value of 0.385 has an area of 0.350 in the upper tail of the normal distribution, therefore an area of 0.700 for a two-sided test. Cheers, Garry ________________________________ From: owner-statalist@hsphsun2.harvard.edu on behalf of Andres Gonzalez Rangel Sent: Fri 03/10/08 00:13 To: statalist@hsphsun2.harvard.edu Subject: st: Two-sided P value for Wilcoxon (Mann-Whitney) rank-sum test Dear Sirs, It is possible to make a two-sided test in a non-parametric command like ranksum? I know that signtest can, but it needs the format "signtest var1 = var2", and I need something like "signtest var, by(group)" which is only allowed with ranksum. The problem is that, contrary to ttest which returns one-sided and two-sided tests of significance for alternative hypothesis, ranksum returns only one P value, which I suppose is a one-sided test of significance for the Ho. . ranksum var, by(group) Two-sample Wilcoxon rank-sum (Mann-Whitney) test group | obs rank sum expected -------------+--------------------------------- no | 39 1842 1794 yes | 52 2344 2392 -------------+--------------------------------- combined | 91 4186 4186 unadjusted variance 15548.00 adjustment for ties -1.98 ---------- adjusted variance 15546.02 Ho: tnfap(group==no) = tnfap(group==yes) z = 0.385 Prob> |z| = 0.7003 I need the Pr of Ho against Ha: diff != 0, like ttest does Thanks in advance for your kind help. Best Regards, Andrés González Rangel Epidemiology Graduate Student Colombia _________________________________________________________________ See how Windows Mobile brings your life together-at home, work, or on the go. http://clk.atdmt.com/MRT/go/msnnkwxp1020093182mrt/direct/01/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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**Follow-Ups**:**st: RE: RE: Two-sided P value for Wilcoxon (Mann-Whitney) rank-sum test***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**References**:**st: Two-sided P value for Wilcoxon (Mann-Whitney) rank-sum test***From:*Andres Gonzalez Rangel <leoangora@hotmail.com>

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