[R-sig-eco] Time series and GLS

[Kingsford Jones]

The gls function in nlme fits a general linear model, so yes you can
have categorical predictors (the advantage over the lm function is the
error covariance matrix may have non-zero off-diagonals, such as with
an autocorrelation structure, and non-constant diagonals).

hth,
Kingsford Jones

On Fri, Jan 1, 2010 at 2:44 PM, LisaB <lisabaril at hotmail.com> wrote:
>
> Hello -
>
> I need to analyze some time series data in an ANOVA framework, but am unsure
> of how to go about it.  I have data on nest success (response) over a 22
> year period for two populations.  For each year I have one value of nest
> success per population.  I am interested in determining 1) whether there are
> differences in nest success over time between these two populations and 2)
> what are the trends for each population over time.  My thought is to use GLS
> and model temporal autocorrelation if the acf function indicates this is an
> issue, but since population is a categorical variable I'm unsure if this is
> appropriate.  Any advice would be much appreciated. Thank you. Lisa
>
>
>
>
> --
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