[R] Error messages using LMER

From: Shige Song <shigesong_at_gmail.com>
Date: Thu 18 Aug 2005 - 18:15:32 EST

Dear All,

After playing with lmer for couple of days, I have to say that I am amazed! I've been using quite some multilevel/mixed modeling packages, lme4 is a strong candidate for the overall winner, especially for multilevel generzlized linear models.

Now go back to my two-level poisson model with cross-classified model. I've been testing various different model specificatios for the past couple of days. Here are the models I tried:

  1. Two level random intercept model with level-1 covariates only m1 <- lmer(.D ~ offset(log(.Y)) + (1|provn) +(1|bcohort) + x1 + x2 , data, poisson, method="Laplace")
  2. Two-level random intercept model with both level-1 and level-2 covariates, but no cross-level interactions: m2 <- lmer(.D ~ offset(log(.Y)) + (1|provn) +(1|bcohort) + x1 + x2 + z1 + z2, data, poisson, method="Laplace")
  3. Two-level random intercept with cross-level interaction m3 <- lmer(.D ~ offset(log(.Y)) + (1|provn) +(1|bcohort) + x1 + x2 + z1 + z2 + x1:z1 + x2:z2, data, poisson, method="Laplace")

Both model 1 and 2 run fine. For model 3, I got error message:

Error in fn(par, ...) : Unable to invert singular factor of downdated X'X In addition: Warning messages:
1: optim or nlminb returned message ERROR: ABNORMAL_TERMINATION_IN_LNSRCH  in: LMEopt(x = mer, value = cv)

2: Leading minor of size 1 of downdated X'X is indefinite

What is going on here? Any workarounds? Thanks!


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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Aug 18 18:19:04 2005

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