[R-sig-ME] Is there a way to deal with errors such as this?

Rolf Turner r@turner @end|ng |rom @uck|@nd@@c@nz
Sun Dec 15 02:20:25 CET 2019

By "this" I mean as demonstrated in the following code.  The file 
testData.txt is attached.

X <- dget("testData.txt")
fit <- glmer(cbind(Dead,Alive) ~ (0+Trt)/Dose + (Dose | Rep),

The foregoing falls over with the (rather complex) error message:

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

I note that mixed_model() from GLMMadaptive seems to be able to deal 
with these data and this model:

fit <- mixed_model(fixed=cbind(Dead,Alive) ~ (0+Trt)/Dose,
                    random=~Dose | Rep,

The foregoing runs without complaint.

I am applying the glmer() model in the context of doing some fairly 
elaborate simulations (in which "X" gets randomly generated) and the 
error causes the simulations to crash unpleasantly.  So I would *like* a 
magic incantation that I can apply in an automated way to prevent the
error from occurring.

I can of course wrap function calls up in try() and if there is an error
generate a new data set and go again.  However I'm a little apprehensive
that this might bias the results of the simulations in some way.

I could also switch to using mixed_model(), but would prefer to stick 
with the devil I know (i.e. glmer()) for the sake of consistency with 
other work that I have done.  (And who knows?  Maybe in the course of 
the simulations mixed_model() might fall over too, from time to time.)

I'd appreciate any avuncular (or materteral) advice that anyone might be 
inclined to offer.



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

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