ALR: Memory and time issues

Cande V Ananth (ananthcv@epi.UMDNJ.EDU)
Mon, 19 Jan 1998 12:16:46 -0500


Fellow SPlus'ers:

I'm attempting to fit a (bivariate) logistic regression model on
a data set containing 9460 obs, using the ALR routine. The
marginal model contains 4 covariates (plus an intercept) and the
pairwise association model contains 5 binary and 2 continuous
covariates. The cluster sizes are all 2 in my data set.

The trouble that I'm encountering is that even after 48 hours, I
don't have the results -- the algorithm seems to be crunching away
to glory ! Simpler models converge rather quickly (less than a minute)
with 3-4 iterations. I don't have any other processes running on my
machine when I invoke SPlus. I've tried several combinations, using
different subsets of covariates both for the marginal model and/or the
pairwise assoc models. Choices of diferent starting values for the
pairwise assoc models still doesn't seem to solve the problem. I have
also tried to build the pairwise association model (with only an
intercept for the marginal mean) which works reasonably quick. The
problem occurs when I specify the complete model for the pairwise assoc,
and 4 covariates for the marginal mean. I don't have problems with
sparce data either.

I have provided reasonably good starting values for the log OR model
(based on crude associations), and the ALR routine fits a GLM to
obtain the starting values for the marginal model parameters. I am
using a SUN Sparc workstation and Splus (version 3.4) operating on
SunOS 5.3

I will greatly appreciate comments on how to get the results without
having to wait for this long !

Some of you may have seen this email in the "Oswald" news group last
week; I apologize for the cross-posting.

---

Cande V. Ananth, PhD, MPH ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The Center for Perinatal Health Initiatives Dept of OB/GYN and Reproductive Sciences Tel: (732) 235-7940 Univ of Medicine and Dentistry of New Jersey Fax: (732) 235-6627 Robert Wood Johnson Medical School ananthcv@EPI.UMDNJ.EDU 125 Paterson St, New Brunswick NJ 08901-1977 http://epi.umdnj.edu/ananth ,,, (o-o) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ooO-(_)-Ooo