Practical information


Theoretical information

Warning Box-Cox strength - species mean changed from smaller than global mean to larger

The Box-cox transformation changed the information in the ecogeographical dataset so much
that the species mean changed from being less than the global mean to greater than the global mean

Variable: Precipitation driest quarter (3 month period)

When run in model with box-cox tranformed variables - Marginality coefficient 0.02
When run with all variable nontransformed Marginality coefficient -0.04
real values – species mean 68.396 mm (n 359), global mean 82.277 mm (n 205031)
box cox transformed values – species mean 3.527892043, global mean 3.398017736


This is only likely to happen if the species mean and global mean are similar.
Therefore to be safe consider the means not be be significantly different for the variables with a absolute marginality of below 0.1. Marginality coeffecients should only be interpreted to one decimal place.

The other option is to run the model with non transformed data


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