[R] Comparing means and trends in short time-series

Dieter Menne dieter.menne at menne-biomed.de
Tue Feb 9 18:33:28 CET 2010

Simone Vincenzi-2 wrote:
>  I have a statistical problem with the comparison of short time-series,
> representing densities of fish in different streams. For each stream (6 in
> total, here below showed only part of the dataset) I have 8 years of
> density
> data, as follows:
>    year density stream
> 1  2000 0.51  stream1
> 2  2001 0.87  stream1
> Are mean densities different among streams from 2000 to
> 2007? Is it sufficient and appropriate a test of correlation (using rcorr
> of
> the library Design, for example) to test if density trends in time are
> similar among streams? 

Have a look at function gls in in package nlme.


There are some similar examples in the book coming with nlme (chapter 5.4)


View this message in context: http://n4.nabble.com/Comparing-means-and-trends-in-short-time-series-tp1474688p1474750.html
Sent from the R help mailing list archive at Nabble.com.

More information about the R-help mailing list