I think it will be better if I explained what I want to do. I have the abundance of Penilia (zooplankter) as y and I have the temperature, salinity and chlorophyll concentration at different depths. I want to know which how the abundance of Penilia is modulate by those environmetal variables and which factors are the most important ones. Please if you can said which are the steps that I have to follow (with the comands if it is possible) and how I can interpret the results. Is very urgent for me, I am waiting to these results to submitt a manuscript. Thank you, Dacha [[alternative HTML version deleted]]