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*Subject*: **[OASIS Issue Tracker] Commented: (OFFICE-2311) ZTEST**

*From*:**OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>***To*: office@lists.oasis-open.org*Date*: Thu, 14 Jan 2010 00:34:15 -0500 (EST)

[ http://tools.oasis-open.org/issues/browse/OFFICE-2311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17482#action_17482 ] Andreas Guelzow commented on OFFICE-2311: ------------------------------------------ please see my proposed solution send to the open-formula list and attached to OFFICE-2300. > ZTEST > ----- > > Key: OFFICE-2311 > URL: http://tools.oasis-open.org/issues/browse/OFFICE-2311 > Project: OASIS Open Document Format for Office Applications (OpenDocument) TC > Issue Type: Sub-task > Components: OpenFormula > Affects Versions: ODF 1.2 > Reporter: Robert Weir > > 5.) ZTEST > > TODO: OOo Calc and Gnumeric produce the same results. Excel (2007 > > beta) claims to calculate the one-tailed test. > > All produce different results than expected! What OOo Calc and > > Gnumeric calculate is out of my scope. Excel tries to calculate the > > probability by integrating from minus infinity to z and substracts > > this from one. That would only be right, if the absolute value of z is > > taken, not the signed z! (I speak already of the one-tailed results > > for this case, so no confusion here.) > > So, either I made a mistake/misinterpretation or all three apps don't > > get it right(TM) > Well, I'll test it in R. There is NO standard z-test, BUT the t-test > will do it, too. [There is also the package 'TeachingDemos' wich does > define the z-test] > > > z.test(x, mu=15, sd=sd(x)) > > > > One Sample z-test > > > > data: x > > z = 0.3111, n = 30.000, Std. Dev. = 8.803, Std. Dev. of the sample mean > > = 1.607, p-value = 0.7557 > > alternative hypothesis: true mean is not equal to 15 > > 95 percent confidence interval: > > 12.34980 18.65020 > > sample estimates: > > mean of x > > 15.5 > where x = 1..30 > This same example gives a value of 0.38 in Calc. I have NO idea what > 0.38 stands for. And I just noticed that it is impossible to compute a > t-test on a single array in Calc against the expected mean - or did I > miss something? > [The t-test in R gives virtually identical results, because a sample > size of 30 is large enough to approximate the z-distribution.] -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://tools.oasis-open.org/issues/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira

**References**:**[OASIS Issue Tracker] Created: (OFFICE-2311) ZTEST***From:*OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>

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