Hello Ecolog-ers,

I'm analysing my Braun-Blanquet cover data for a group of vegetation
structure variables (in diff habitat types) and am having trouble finding a
definitive way to do this legitimately with mixed effects models, ANOVAs and
ordinations.

The issue is that the BB scale is an ordinal scale. Many studies have simply
taken midpoint values of the scale classes and turned the ordinal data into
a metric and analysed from there. To me this seems a bit dodgy, given that
there are really only 9 values that these variables can take, rather than
the 100 values that is implicit in the metric percentage of cover.

I have read Podani's many papers on the issues and potential solutions for
ordinations but I seem to be finding it more difficult to find literature
with mixed effects models, or any kind of regression-based model.

Has anyone else encountered these problems? Can anyone suggest some current
literature on the matter?

Thank you kindly,
Liz



-- 
Liz Pryde
PhD Candidate (off-campus)
School of Earth and Environmental Sciences
James Cook University

Thornbury, Melbourne

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