[R] nonmonotonic glm?

[Stanislav Aggerwal]

I have the following problem.
DV is binomial p
IV is quantitative variable that goes from negative to positive values.

The data look like this (need nonproportional font to view):
o                                     o
      o                      o
          o           o
             o     o
                o


----------------------+------------------------
                           0

If these data were symmetrical about zero, I could use abs(IV) and do glm(p
~ absIV).
I suppose I could fit two glms, one to positive and one to negative IV
values. Seems a rather ugly approach.

(To complicate things further, this is within-subjects design)

Any suggestions welcome. Thanks!

Bill

	[[alternative HTML version deleted]]