nnet() fit criteria

Hi all,

I'm using nnet() for non-linear regression as in Ch8.10 of MASS. I 
understand that nnet() by default optimizes least squares. I'm looking 
to have it instead optimize such that the mean error is zero (so that it 
is unbiased). Any suggestions on how this might be achieved?

Cheers,

Mike

Mike Lawrence
http://artsweb.uwaterloo.ca/~m4lawren

"The road to wisdom? Well, it's plain and simple to express:
Err and err and err again, but less and less and less."
- Piet Hein