Multiple regression and/or classification and regression trees

[Bree Witteveen]

I am in the midst of doing analysis for my dissertation and would really
appreciate some help.
I am exploring the relationships between stable carbon and nitrogen
isotope ratios (continuous variables) and various predictors such as
latitude, longitude, month, and year. I then want to use the
relationships to see if the isotope ratios on their own can predict the
location from which they came. So far I have done simple linear
regression between each ratio and each predictor. I also did a series of
ANOVAs. I followed these with discriminant function analyses and had
fairly decent results. However, I have been advise to alter my approach
and "test for non-linear relationships, either with polynomial
regression or GAMs" and to classify using classification and regression
trees rather than DFA.
I am currently using the SPSS 15.0 grad pack and can't see to determine
if these analyses are possible in my package. If they are, I don't know
how to execute them. HELP!
Thanks in advance!

--
Briana H. Witteveen
Doctoral Candidate

University of Alaska Fairbanks
University of Central Florida
Physiological Ecology and Bioenergetics Lab
118 Trident Way
Kodiak, AK 99615
Office: [phone]
Mobile: [phone]

=====================
To manage your subscription to SPSSX-L, send a message to
[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
SIGNOFF SPSSX-L
For a list of commands to manage subscriptions, send the command
INFO REFCARD