[R] ks.test troubles

[Martin Kaffanke]

Am Samstag, den 08.03.2008, 19:34 +0100 schrieb Uwe Ligges:
> 
> Martin Kaffanke wrote:
> > Hi there!
> > 
> > I have two little different data.  One is a computer test on people, the
> > other is a paper and pencil test.  two boxplots show me that the data is
> > almost the same.
> > 
> > So now I'd like to know if I could handle all data as one, by testing
> > with ks.test:
> > 
> > ====
> >> ks.test(el$angststoer, fl$angststoer)
> > 
> >         Two-sample Kolmogorov-Smirnov test
> > 
> > data:  el$angststoer and fl$angststoer 
> > D = 0.1413, p-value = 0.9112
> > alternative hypothesis: two-sided 
> > 
> > Warning message:
> > In ks.test(el$angststoer, fl$angststoer) :
> >   cannot compute correct p-values with ties
> > ====
> > 
> > Ok, so how can I get the p-value?
> 
> 
> You already got it, it is 0.9112, but since you have ties in your data, 
> R warns you about it (it's not an error, just a warning). And indeed, 
> you have some ties in fl$angststoer.

Thanks,
But what exactly are ties?  And how can I interpret the answers?  (I'm
not sure about the german translation, and the translations don't give
me a hint.

Thanks,
Martin

> 
> Uwe Ligges
> 
> 
> 
> > I tried two tests:
> > ====
> >> ks.test(fl$angststoer, "dnorm")
> > 
> >         One-sample Kolmogorov-Smirnov test
> > 
> > data:  fl$angststoer 
> > D = 0.8109, p-value < 2.2e-16
> > alternative hypothesis: two-sided 
> > 
> > Warning message:
> > In ks.test(fl$angststoer, "dnorm") :
> >   cannot compute correct p-values with ties
> > ====
> > 
> > so I see that this message in the first one, depends on fl$angststoer.
> > 
> > The I have on this two vectors:
> > 
> > ====
> >> fl$angststoer
> >  [1]  1.22184871 -0.30103000  1.00000000 -1.30103000  0.69897000
> > -0.30103000
> >  [7] -2.30103000 -1.00000000 -2.00000000  0.22184832 -1.77819468
> > -0.30103000
> > [13] -2.00000000 -0.30103000 -0.30103000  0.22184832 -0.90308999
> > -1.14611935
> > [19] -1.30103000 -3.20411998 -0.60205999 -2.25531594 -3.60205999
> > -1.30103000
> > [25] -2.30103000 -0.07918038 -2.14599777  0.74472745 -3.30103000
> > -0.30103000
> > [31] -0.30103000 -4.30103000 -0.60205999 -0.14612847 -1.30103000
> > -1.30103000
> > [37]  0.00000000 -0.17609234 -0.47711908 -1.77819468 -1.00000000
> > -1.20411998
> > [43] -0.07918038 -2.00000000 -2.00000000 -1.30103000
> >> el$angststoer
> >  [1] -2.2407100 -2.8601209 -0.5005659 -2.4007721 -0.3474336 -2.6653452
> >  [7]  0.6548865 -1.6281751 -1.2940679 -0.1316566 -1.4541612 -1.6560206
> > [13] -0.7441850  0.8219399  0.1746081 -1.2314248 -3.8910969  0.1328448
> > [19] -1.8439508 -0.8833972 -0.4936052 -0.1664593 -0.8694749 -2.8253588
> > ====
> > 
> > Doesn't seem to be a problem?
> > 
> > What can I do for a good computation?
> > 
> > Thanks,
> > Martin
> > 
> > 
> > 
> > 
> > 
> > ------------------------------------------------------------------------
> > 
> > ______________________________________________
> > 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.
-- 
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Martin Kaffanke +43 650 4514224
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