Hey,
I don't really get the output of the performed Levene's test.
So in short.
two data sets, one with 75 elements, one with 283.
And I want to check whether they have the same variance.
I did a LeveneTest
And this is the output:
Levene's Test for Homogeneity of Variance (center = median)
Df F value Pr(>F)
group 1 10.948 0.001033 **
356
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05
'.' 0.1 ' ' 1
So I would think that H0 is being rejected? for everything except 99.9%?
But what does the 356 mean?
Is this test performed correctly? group is a vector with 1's and 2's
appointing the two datasets...
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> I don't really get the output of the performed Levene's test.One answer would be to read John Fox's rather good book, for which car is the corresponding R package. Another is to look up leven'es test; a reasonably authoritative web reference for the calculation is http://www.itl.nist.gov/div898/handbook/eda/section3/eda35a.htm if you followed that, you would find that 356 turns up somewhere important ... A clue: It is unlikely to be coincidence that you have 358 data points in 2 groups.... and that the 356 turns up in the column headed "Df" in the leveneTest output. S Ellison ******************************************************************* This email and any attachments are confidential. Any use...{{dropped:8}}
Hello, The Pr(>F) is a regular p-value, with the usual meaning. Rui Barradas Em 21-06-2013 11:05, pieter escreveu:> k. > Thanks. > Sorry i'm not the biggest statician, but I still find the output write > out not the clearest of all. Anyway, that is probably a personal > problem. :-) > > Just one question. the Pr(>F) is just the regular p value, right? so > above the treshold means equal variance? > > Thanks alot. > > Pieter > > On vr 21 jun 2013 11:56:06 CEST, Rui Barradas wrote: >> Hello, >> >> You need to know what is the Levene test, that output is as clear as >> water. 75 + 283 == 358. Minus two groups gives 356. >> See >> >> http://en.wikipedia.org/wiki/Levene%27s_test >> >> Hope this helps, >> >> Rui Barradas >> >> Em 21-06-2013 09:12, pieter escreveu: >>> Hey, >>> I don't really get the output of the performed Levene's test. >>> So in short. >>> two data sets, one with 75 elements, one with 283. >>> And I want to check whether they have the same variance. >>> >>> I did a LeveneTest >>> And this is the output: >>> >>> Levene's Test for Homogeneity of Variance (center = median) >>> Df F value Pr(>F) >>> group 1 10.948 0.001033 ** >>> 356 >>> --- >>> Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 >>> >>> So I would think that H0 is being rejected? for everything except 99.9%? >>> But what does the 356 mean? >>> Is this test performed correctly? group is a vector with 1's and 2's >>> appointing the two datasets... >>> >>> >>> >>> [[alternative HTML version deleted]] >>> >>> ______________________________________________ >>> R-help at r-project.org mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-help >>> PLEASE do read the posting guide >>> http://www.R-project.org/posting-guide.html >>> and provide commented, minimal, self-contained, reproducible code. >>>
Dear pieter, On Fri, 21 Jun 2013 10:12:26 +0200 pieter <dencoussie at gmail.com> wrote:> Hey, > I don't really get the output of the performed Levene's test. > So in short. > two data sets, one with 75 elements, one with 283. > And I want to check whether they have the same variance. > > I did a LeveneTest > And this is the output: > > Levene's Test for Homogeneity of Variance (center = median) > Df F value Pr(>F) > group 1 10.948 0.001033 ** > 356 > --- > Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 > > So I would think that H0 is being rejected? for everything except 99.9%?0.001033 is the p-value for the null hypothesis of equal variances.> But what does the 356 mean?The residual df for the test.> Is this test performed correctly?I certainly hope so. John ------------------------------------------------ John Fox Sen. William McMaster Prof. of Social Statistics Department of Sociology McMaster University Hamilton, Ontario, Canada http://socserv.mcmaster.ca/jfox/> group is a vector with 1's and 2's > appointing the two datasets... > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.