[R-sig-ME] glmer and influence.me - complaining about nAGQ==0

[John Fox]

Dear Catia,

I believe I understand what's going on: influence.merMod() works by 
updating the model -- it calls update() -- using the parameter estimates 
for the fit to the full data as start-values. The idea is to decrease 
the computation necessary for each re-fit.

It probably would have been better if I had made this an option, with 
using the start-values as the default, but perhaps there's a work-around:

You may be able to fit your model without specifying nACQ by instead 
specifying the estimates that you obtained as start-values. Then glmer() 
may converge quickly. If it doesn't, that would, I suppose, indicate 
some sort of ill-conditioning.

Ben might well have something to add.

I hope this helps,
  John

John Fox, Professor Emeritus
McMaster University
Hamilton, Ontario, Canada
web: https://socialsciences.mcmaster.ca/jfox/

On 2021-04-24 2:29 p.m., Cátia Ferreira De Oliveira via 
R-sig-mixed-models wrote:
> Dear Professor Bolker,
> 
> I am really sorry for bothering you but I have been quite stuck and have
> posted my question both on reddit and cross validated but nothing has come
> from it. Do you know if there is a good way of running dfbetas for glmer
> with a gamma distribution?  The model runs without issues,
> 
> lmer_log11 <- glmer(logRT ~ Probability*Block*Session*testing + (1 +
> Block * Probability * Session|Participant), data= Data, family =
> Gamma(link = "log"),
> control=glmerControl(optimizer="bobyqa",optCtrl=list(maxfun=1000000)),
> nAGQ = 0)
> 
> yet when I run the influence function I get this error:
> 
> influentialcases <- influence(glmer_log11, "Participant")
> 
> Error in glmer(formula = RT ~ Probability * Block * Session * testing +  :
>    should not specify both start$fixef and nAGQ==0
> 
> I have tried to remove the "nAGQ==0" but the model is now taking 10 days to
> converge, a lot more than usual. Given this, I haven't been able to check
> if the influential cases will run normally.
> 
> Do you have any idea why this is happening? I would very much
> appreciate your help!
> 
> Thank you so much!
> 
> Best wishes,
> 
> 	[[alternative HTML version deleted]]
> 
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