[R-sig-eco] R-sig-ecology Digest, Vol 135, Issue 8

[Peter Nelson]

What does a time series approach have to offer? I’m away from my usual resources and can’t recall the the terms I think might be relevant (or even helpful), but suggest looking for a cluster analysis applicable to a ts that may provide a partial solution. 

Let us know what you come up with!

Cheers, Pete

Sent from my iPhone

> On Jun 15, 2019, at 13:00, r-sig-ecology-request using r-project.org wrote:
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> Today's Topics:
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>   1. Doing repeated measures on a randomized block design
>      (Richard Boyce)
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Fri, 14 Jun 2019 18:41:47 +0000
> From: Richard Boyce <boycer using nku.edu>
> To: "r-sig-ecology using r-project.org" <r-sig-ecology using r-project.org>
> Subject: [R-sig-eco] Doing repeated measures on a randomized block
>    design
> Message-ID: <0B581062-D8DA-435D-87D0-BC99FED2D151 using nku.edu>
> Content-Type: text/plain; charset="utf-8"
> 
> I’m measuring chlorophyll fluorescence (FvFm), my measured variable, on N and S exposures (treatment variable) of 4 red cedar trees. Here’s what the beginning of the data file looks like: 
> 
> head(perm.fvfm).
> 
>  Tree Exposure   Date  FvFm
> 1    1        S 13.Feb 0.775
> 2    1        N 13.Feb 0.795
> 3    2        S 13.Feb 0.737
> 4    2        N 13.Feb 0.759
> 5    3        S 13.Feb 0.615
> 6    3        N 13.Feb 0.712
> 
> If I were just doing this one time, this would be a randomized block design, where trees were the blocks (random variable) and exposure was the treatment variable (fixed variable). Actually, since there are only two treatment levels, it would be a paired t-test.
> 
> However, I’ve repeated this on many dates (18 so far this year). So this also requires a repeated-measures design, with trees as subjects. 
> 
> Repeated-measures, however, usually have time (date) as a within-subject variable and then some other treatment that is a between-subjects variable. I don’t have have a between-subjects variable, however, as all subjects (trees) get both levels of exposure and all levels of time (date).
> 
> I’ve searched the web, but there is not a lot out there for this kind of design. It looks like lm, lme, lmer, and permuco in R might all work, but advice for how to set up the Error() or random variable designations are confusing and sometimes contradictory. Any advice would be much appreciated!
> 
> Thanks,
> Rick Boyce
> 
> 
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> End of R-sig-ecology Digest, Vol 135, Issue 8
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