Prev 5984 / 7420 Next

R-sig-ecology Digest, Vol 135, Issue 8

Peter Nelson

Sat, Jun 15, 2019 9:20 PM

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

   https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
or, via email, send a message with subject or body 'help' to
   r-sig-ecology-request at r-project.org

You can reach the person managing the list at
   r-sig-ecology-owner at r-project.org

When replying, please edit your Subject line so it is more specific
than "Re: Contents of R-sig-ecology digest..."


Today's Topics:

  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 at nku.edu>
To: "r-sig-ecology at r-project.org" <r-sig-ecology at r-project.org>
Subject: [R-sig-eco] Doing repeated measures on a randomized block
   design
Message-ID: <0B581062-D8DA-435D-87D0-BC99FED2D151 at 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



------------------------------

Subject: Digest Footer

_______________________________________________
R-sig-ecology mailing list
R-sig-ecology at r-project.org
https://stat.ethz.ch/mailman/listinfo/r-sig-ecology


------------------------------

End of R-sig-ecology Digest, Vol 135, Issue 8
*********************************************