ks.test troubles
Martin Kaffanke wrote:
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$angststoer.
Thanks, But what exactly are ties?
Theory says that there are no ties (german: Bindungen), hence R warns. But with p=0.9, I won't care about that at all. It might be interesting with p close to alpha. In fact, I also would not "handle all data as one", but simply add a factor variable that distinguishes computer from pencil tests so you can inspect it in further analyses... Uwe Ligges
And how can I interpret the answers? (I'm not sure about the german translation, and the translations don't give me a hint. Thanks, Martin
Uwe Ligges
I tried two tests: ====
ks.test(fl$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 ------------------------------------------------------------------------
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