[R-sig-ME] Error from glmer() that I do not understand.

[Rolf Turner]

Dear All,

In the course of some convoluted floundering around, I got a rather 
unexpected error from glmer().  Here are the data set and the call:

Xdemo <- structure(list(Dead = c(4, 26, 71, 34, 67, 68, 32, 39, 2, 15,
64, 26, 29, 0, 11, 10, 89, 87, 30, 121, 2, 9, 20, 0, 4, 30, 21,
21, 48, 54, 0, 47, 73, 87, 33, 73, 41, 39, 0, 25, 33, 19, 53,
39, 20, 3, 26, 26, 80, 79, 9, 35, 39, 40, 81, 80, 103, 7, 63,
92, 89, 40, 76, 0, 30, 29, 44, 64, 24, 72, 49, 0, 72, 73, 78,
46, 3, 21, 34, 29, 25, 37, 52, 64, 49, 0, 11, 11, 0, 17, 13,
56, 28, 3, 19, 23, 21, 26, 33), Alive = c(50, 22, 16, 6, 6, 1,
1, 0, 45, 5, 3, 0, 0, 55, 70, 18, 24, 4, 0, 0, 27, 11, 1, 35,
23, 17, 0, 0, 0, 0, 30, 12, 4, 1, 0, 0, 0, 0, 35, 29, 11, 6,
5, 2, 0, 61, 21, 7, 1, 0, 13, 0, 0, 0, 0, 0, 0, 26, 0, 0, 0,
0, 0, 26, 30, 5, 0, 0, 0, 0, 0, 74, 24, 11, 0, 0, 18, 11, 0,
0, 14, 6, 6, 8, 0, 40, 17, 9, 22, 38, 11, 2, 0, 51, 10, 5, 3,
0, 0), Rep = structure(c(6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 12L,
12L, 12L, 12L, 12L, 18L, 18L, 18L, 18L, 18L, 18L, 18L, 3L, 3L,
3L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 15L, 15L, 15L, 15L, 4L, 4L, 4L,
4L, 10L, 10L, 10L, 10L, 10L, 10L, 10L, 16L, 16L, 16L, 16L, 16L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 7L, 7L, 7L, 7L, 7L, 7L, 13L, 13L,
13L, 13L, 13L, 13L, 13L, 13L, 5L, 5L, 5L, 5L, 5L, 11L, 11L, 11L,
11L, 17L, 17L, 17L, 17L, 17L, 2L, 2L, 2L, 8L, 8L, 8L, 8L, 8L,
14L, 14L, 14L, 14L, 14L, 14L), .Label = c("1", "2", "3", "4",
"5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15",
"16", "17", "18"), class = "factor"), Dose = c(0, 15, 30, 45,
55, 65, 75, 85, 0, 30, 40, 60, 80, 0, 10, 20, 30, 40, 60, 80,
0, 10, 35, 0, 10, 20, 35, 40, 45, 50, 0, 25, 30, 35, 30, 45,
50, 55, 0, 15, 20, 25, 30, 35, 40, 0, 10, 15, 25, 35, 0, 10,
15, 18, 21, 24, 27, 0, 10, 18, 21, 24, 37, 0, 8, 12, 15, 18,
22, 20, 24, 0, 10, 14, 26, 30, 0, 4, 8, 13, 4, 8, 10, 12, 18,
0, 6, 9, 0, 3, 6, 13, 18, 0, 6, 8, 10, 12, 14), Trt = structure(c(6L,
6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L,
6L, 6L, 6L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
3L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L,
5L, 5L, 5L, 5L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
2L, 2L), .Label = c("16hour10deg", "16hour20deg", "16hour5deg",
"8hour10deg", "8hour20deg", "8hour5deg"), class = "factor")), class = 
"data.frame", row.names = c(1L,
2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 11L, 12L, 14L, 15L, 16L, 17L,
18L, 19L, 20L, 22L, 23L, 24L, 25L, 26L, 28L, 29L, 30L, 31L, 32L,
33L, 34L, 35L, 38L, 39L, 40L, 43L, 45L, 46L, 47L, 48L, 49L, 50L,
51L, 52L, 53L, 54L, 55L, 56L, 57L, 59L, 61L, 63L, 64L, 65L, 66L,
67L, 68L, 69L, 71L, 72L, 73L, 74L, 75L, 76L, 77L, 78L, 79L, 80L,
81L, 82L, 83L, 84L, 85L, 87L, 88L, 90L, 91L, 92L, 93L, 94L, 95L,
98L, 99L, 100L, 101L, 104L, 105L, 106L, 107L, 111L, 112L, 113L,
115L, 116L, 117L, 120L, 121L, 122L, 123L, 124L))

library(lme4)
fit <- glmer(cbind(Dead,Alive) ~ (Trt+0)/Dose +
              (Dose | Rep),
               data=Xdemo,
               family=binomial(link="logit"),nAGQ=0)

This throws the error:

> Error in pwrssUpdate(pp, resp, tol = tolPwrss, GQmat = GHrule(0L), compDev = compDev,  : 
>   (maxstephalfit) PIRLS step-halvings failed to reduce deviance in pwrssUpdate

Setting nAGQ=1 makes no difference.

The data set "Xdemo" does not seem to me to be unduly weird.  It is 
reasonably balanced, with reasonably large values of the binomial sample 
sizes.  There are 99 observations in total, which again seems to me to 
be a reasonable number.

Is there anything that I can do about this error, or do I just have to 
live with it?

Thanks for any advice.

cheers,

Rolf Turner

-- 
Honorary Research Fellow
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276