[R] Kolmogorov Smirnov Test

Kerry kbrownk at gmail.com
Thu Nov 11 05:22:55 CET 2010


I'm using ks.test (mydata, dnorm) on my data. I know some of my
different variable samples (mydata1, mydata2, etc) must be normally
distributed but the p value is always < 2.0^-16 (the 2.0 can change
but not the exponent).

I want to test mydata against a normal distribution. What could I be
doing wrong?

I tried instead using rnorm to create a normal distribution: y = rnorm
(68,mean=mydata, sd=mydata), where N= the sample size from mydata.
Then I ran the k-s: ks.test (mydata,y). Should this work?

One issue I had was that some of my data has a minimum value of 0, but
rnorm ran as I have it above will potentially create negative numbers.

Also some of my variables will likely be better tested against non-
normal distributions (uniform etc.), but if I figure I should learn
how to even use ks.test first.

I used to use SPSS but am really trying to jump into R instead, but I
find the help to assume too heavy of statistical knowledge.

I'm guessing I have a long road before I get this, so any bits of
information that may help me get a bit further will be appreciated!

Thanks,
kbrownk



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