Multiple comparison for circular data

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Multiple comparison for circular data

Xiaohua Dai
Hi All,

Does anyone know how to compare the means of several circular-data
samplings? Any related websites, references and softwares?

Thanks
Xiaohua

--
Xiaohua Dai, Dr.

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Re: Multiple comparison for circular data

Spencer Graves
          I just got 141 hits from 'RSiteSearch("circular data")'.  From this,
I quickly learned of two contributed packages for circular data:
"circular" and "CircStats".  Both seem to be current, and both are
maintained by the same person.

          If you can compute a likelihood for a particular model, then you can
test for equality of parameters between two data sets as follows:

          logLik1 = log(likelihood for data set 1 fit by itself.
          logLik2 = log(likelihood for data set 2 fit by itself.
          logLik12= log(likelihood for data sets 1 and 2 fit as one.

          log(likelihood ratio) = (logLik1+logLik2-logLik12).

          If k parameters are fit for each model, then 2*log(likelihood ratio)
should be approximately chi-square(k).  From this you can get a p-value
to compare any pair of data sets.  Then use Bonferroni, multiplying each
p-value by, say, (k-1).  Any p-value(s) below your Bonferroni-adjusted
threshold could be claimed to be significantly different.

          If this is not adequate, I suggest you download both packages (if you
have not already), try them, and then send a question to the maintainer.
  If you would like more help from the listserve, I suggest you PLEASE
do read the posting guide! "www.R-project.org/posting-guide.html".
Also, please install the "fortunes" package and read especially
fortune('posting').

          hope this helps.
          spencer graves

ecoinfo wrote:

> Hi All,
>
> Does anyone know how to compare the means of several circular-data
> samplings? Any related websites, references and softwares?
>
> Thanks
> Xiaohua
>
> --
> Xiaohua Dai, Dr.
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

______________________________________________
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