[R-sig-ME] GLMM -Firefly Flash

Vickly Mobilim vickmoe7 at gmail.com
Tue Nov 22 18:01:11 CET 2016


I've read several writing of yours about GLMM and I thought it would be the
best tool to answer my research questions. However, I wasn't sure if I
really need it and my data permit me to use it. That said, I have 78
individuals of firefly divided into four groups (A= 20 indv., B = 20 indv.,
C = 20 indv. and D = 18 indv.). This is due to several limitations that I
can't take more samples of firefly. I will explain the details of the
experiment below.

I'm hoping that you can advise me on this issue, whether you have seen such
cases of low sample size using GLMM or whether GLMM is not suitable for my

I expose the fireflies with several intensity of white light according to
their group (Group A = 0.05lux, B = 0.1lux, C = 0.3lux and D = 0.5lux) then
measure their flash rates and duration before, during and after exposure to
light (repeated measure design). Temperature, humidity and individual
eye-to-body size ratio were also measured. My main aim was to measure the
impact of several light pollution intensity to their flash rates and
duration and taking temperature, humidity and eye-to-body size into account.

I realized that calculating changes in their flash rates and duration are
achievable by subtracting post-experiment result with pre-experiment result
then use unpaired t-test to compare the results. However, my data was not
normal and I used Mann-Whitney U test instead. But this does not take
temperature, humidity and eye-to-body size into account. As I was looking
into the possibility of taking them into account, I found several modelling
technique that is suitable including GLMM but I am not sure if I can employ
them because according to a statistician I am in consult with, the sample
size is too small to be developed into a model that it would invite more
problem in analysis.

Vickly Mobilim

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