From: WeiWei Shi <helprhelp_at_gmail.com>

Date: Sat 23 Apr 2005 - 08:46:37 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Apr 23 08:51:12 2005

Date: Sat 23 Apr 2005 - 08:46:37 EST

hope it is not b/c some central limit therory, otherwise my initial plan will fail :)

On 4/22/05, WeiWei Shi <helprhelp@gmail.com> wrote:

> Hi, r-gurus:

*>
**> I happened to have a question in my work:
**>
**> I have a dataset, which has only one dimention, like
**> 0.99037297527605
**> 0.991179836732708
**> 0.995635340631367
**> 0.997186769599305
**> 0.991632565640424
**> 0.984047197106486
**> 0.99225943762649
**> 1.00555642128421
**> 0.993725402926564
**> ....
**>
**> the data is saved in a file called f392.txt.
**>
**> I used the following codes to play around :)
**>
**> k<-read.table("f392.txt", header=F) # read into k
**> kk<-k[[1]]
**> l<-qqnorm(kk)
**> diff=c()
**> lenk<-length(kk)
**> i=1
**> while (i<=lenk){
**> diff[i]=l$y[i]-l$x[i] # save the difference of therotical quantile
**> and sample quantile
**> # remember, my sample mean is around 1
**> while the therotical one, 0
**> i<-i+1
**> }
**> hist(diff, breaks=300) # analyze the distr of such diff
**> qqnorm(diff)
**>
**> my question is:
**> from l<-qqnorm(kk), I wanted to know, from which point (or cut), the
**> sample points start to become away from therotical ones. That's the
**> reason I played around the "diff" list, which gives me the difference.
**> To my surprise, the diff is perfectly normal. I tried to use some
**> kk<-c(1, 2, 5, -1 , ...) to test, I concluded it must be some
**> distribution my sample follows gives this finding.
**>
**> So, any suggestion on the distribution of my sample? I think there
**> might be some mathematical inference which can leads this observation,
**> but not quite sure.
**>
**> btw,
**> > fitdistr(kk, 't')
**> m s df
**> 9.999965e-01 7.630770e-03 3.742244e+00
**> (5.317674e-05) (5.373884e-05) (8.584725e-02)
**>
**> btw2, can anyone suggest a way to find the "cut" or "threshold" from
**> my sample to discretize them into 3 groups: two tail-group and one
**> main group.--------- my focus.
**>
**> Thanks,
**>
**> Ed
*

>

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Apr 23 08:51:12 2005

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