[R] Help with short time series

Dieter Menne dieter.menne at menne-biomed.de
Mon Aug 7 11:53:11 CEST 2006

Simone Vincenzi <simone.vincenzi <at> nemo.unipr.it> writes:

> Dear R-list, 
> I have a statistical problem with the comparison of two short time-series of 
> density data in an ecological framework. I have to compare two short time 
> series (5 years, one value for each year) of species density data (it is the 
> density of fish in two different streams) to test if the two means of the 
> five densities are significantly different, so basically if the two mean 
> stream-specific fish densities are significantly different. 
> I don't think I can use a straight t-test due to the problem of 
> autocorrelation and I don't think I can use a repeated measure ANOVA as I 
> don't have any replicates. 
> Any help would be greatly appreciated. 

try something like 


This should also give you an estimate if the slopes are different if you test
against the simplified model


Since you did not provide a short example data set, this is only approximatively


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