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Article #218Re: IQRs and hypothesis testing
From: Roger D Nelson
Date: Thu, 16 Apr 1992 15:36
Date: Thu, 16 Apr 1992 15:36
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In article <1992Apr15.233135.2693@newshost.anu.edu.au> Andrew.Robinson@anu.edu.au writes: >In article <OLIVER.92Apr15054328@ballard1.mit.edu> oliver@athena.mit.edu (James >D. Oliver III) writes: >>I was using a packaged statistical program to do some simple means testing, >>and notice that in several cases the program didn't do a straightforward >>t-test, but instead "computed the standard error of the difference of means >>assuming IQR(pop.1)/IQR(pop.2)= X". >> >>I found out what IQR is (interquartine(sp?) range) and have a general > ^^^^^^^^^^^^^ [interquartile]? >>understanding of what it is, but can find no references on the specifics of >>this particular adjustment and/or the justification for using it. >> >Sounds to me like the package is trying to determine the relative spreads of >the populations because the t-test fails when testing on populations with >differing variances. The ANOVA does as well, but I don't know of a comparable >procedure. In fact, that's the first time I've heard of a package which tries >to do this. Nice. > >But I have _no_ idea where to go from here. > If indeed the variances are so different the package sees the t-test as inappropriate, you might consider looking at the distributions themselves, then looking toward some applicable non-parametric test.
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arc1-ca.pugleaf.net!sparky!uunet!zaphod.mps.ohio-state.edu!qt.cs.utexas.edu!yale.edu!jvnc.net!rutgers!kb2ear!princeton!phoenix.Princeton.EDU!rdnelsonReferences:
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Path: arc1-ca.pugleaf.net!sparky!uunet!zaphod.mps.ohio-state.edu!qt.cs.utexas.edu!yale.edu!jvnc.net!rutgers!kb2ear!princeton!phoenix.Princeton.EDU!rdnelson From: rdnelson@phoenix.Princeton.EDU (Roger D Nelson) Newsgroups: sci.math.stat Subject: Re: IQRs and hypothesis testing Message-ID: <1992Apr16.153628.23100@Princeton.EDU> Date: 16 Apr 92 15:36:28 GMT References: <OLIVER.92Apr15054328@ballard1.mit.edu> <1992Apr15.233135.2693@newshost.anu.edu.au> Sender: news@Princeton.EDU (USENET News System) Organization: Princeton University Lines: 24 Originator: news@ernie.Princeton.EDU Nntp-Posting-Host: phoenix.princeton.edu