[R-sig-eco] lme4 for pseudoreplication avoidance

[ONKELINX, Thierry]

Dear Lara,

I think you want

lmer(AntSize  ~ ColonySize + (1|ColonyID))

Best regards,

ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht
Belgium
+ 32 2 525 02 51
+ 32 54 43 61 85
Thierry.Onkelinx at inbo.be
www.inbo.be

To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of.
~ Sir Ronald Aylmer Fisher

The plural of anecdote is not data.
~ Roger Brinner

The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data.
~ John Tukey


-----Oorspronkelijk bericht-----
Van: r-sig-ecology-bounces at r-project.org [mailto:r-sig-ecology-bounces at r-project.org] Namens Lara R. Appleby 04
Verzonden: maandag 25 februari 2013 7:32
Aan: r-sig-ecology at r-project.org
Onderwerp: [R-sig-eco] lme4 for pseudoreplication avoidance

I am following a suggestion from http://www.coloss.org/beebook/I/invitro/3/1to
use nesting in my analyses of measurements of individual worker ants within multiple colonies.

"y" is a worker-level trait (e.g. the size of an individual worker ant) measured once for each individual worker in the study "a" is the colony ID "b" is a colony-level trait (e.g. colony size at the beginning of the experiment) measured once for each colony in the study

All of the workers ("y") in a colony share an "a" value and a "b" value.

I want to know the independent effects of a and b on y, accounting for the non-independence of worker-level observations.

How do I code this kind of model?

I get as far as:

lme4 (y~a+b)

but I don't know how to code the nesting bit in this case.

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