# [R] Problem with geeglm

From: Rick Bilonick <rab45+_at_pitt.edu>
Date: Sat 26 Aug 2006 - 08:41:34 EST

event.nab.2 is 0/1 and I dichotomized va to get va.2 to see if I could get geeglm to work. glm has no problem with the data but geeglm chokes. Each subject (patient.id) has at most 2 observations and more than 3/4 of the subjects have 2 observations. I have even worse problems trying to use glmmPQL from MASS and worse still trying to use lmer from lme4. But I figured a marginal model would work. (geeglm seems to work OK with most of the explanatory factors in the data set I have but a couple of them show similar problems.)

Call:
glm(formula = event.nab.2 ~ va.2, family = binomial(link = "logit"),

data = test)

Deviance Residuals:

Min 1Q Median 3Q Max -0.3787 -0.3787 -0.2246 -0.2246 2.7177

Coefficients:

```              Estimate Std. Error z value Pr(>|z|)
(Intercept)    -2.5993     0.1804  -14.41  < 2e-16 ***
va.2(84, Inf]  -1.0685     0.3435   -3.11  0.00187 **
```
```---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

(Dispersion parameter for binomial family taken to be 1)

Null deviance: 363.19  on 958  degrees of freedom
Residual deviance: 352.28  on 957  degrees of freedom
AIC: 356.28

Number of Fisher Scoring iterations: 6

Error in geese.fit(xx, yy, id, offset, soffset, w, waves = waves,
zsca,  :
nrow(zsca) and length(y) not match

patient.id event.nab.2      va.2
1          1           0 (-Inf,84]
2          1           0 (-Inf,84]
3          2           0 (84, Inf]
4          2           0 (84, Inf]
5          3           0 (84, Inf]
6          3           0 (84, Inf]

I'm using R 2.3.1 and the latest version of geepack. I get a similar
error message if I use va which is continuous.

I don't know what the error message from geeglm/geese means.

Rick B.

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