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]]
>
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