85

ECOM II

 It is often the case that species vary greatly in abundance, over possibly 5 or more

orders of magnitude. When there is great variation in abundance consider making a

square root transformation. A log transformation might also be useful but most

species data sets include many zeros so you would need to use a log x+1

transformation and this can be misleading is there are many low abundance species.

During this preliminary stage you should also check for zero sum rows and columns in

your data sets as these will likely cause division by zero problems

later. This is done using the Handling zeros radio button on the Working data tabs.

Having completed these initial inspections we must now Examine and Select

Environmental Variables.

Interpreting the results

Copyright 2004  PISCES Conservation Ltd