Joshua B Robins wrote:
Hello,
I'm trying to figure out how to run the stepAIC function starting with the
NULL model. I can call the null model (e.g., lm(y ~ NULL)), but using
this object in stepAIC doesn't seem to work.
I don't know what doesn't seem to work means here, but your null
model is equivalent to lm(y ~ 1) and stepAIC handles both just fine
for me. Did you specify 'scope' with an 'upper' component?
Peter Ehlers
The objective is to calculate AICc. This can be done if stepAIC can be
run starting with the NULL model; the (2p(p-1)/(n-p-1))to get AICc would
be added to the final step AIC value. Can anyone suggest how to run
stepAIC beginning with the NULL model, and sequentially adding and
removing variables (essentially a bottom-up approach)?
Thanks,
Josh Robins
School of Fisheries and Ocean Sciences
University of Alaska Fairbanks
Juneau Center
(206) 331-8633
[EMAIL PROTECTED]
http://students.washington.edu/jbrobins
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