[R-sig-ME] What does that mean?

[Ben Bolker]

  More generally (mostly lme4 maintainers will care about this): I
suspect that the PIRLS warning is most often thrown when an NaN occurs
within the computations done in C++ code for *any* reason (predictions
outside of the domain of the link function, complete separation, weirdly
misspecified models, etc.). Figuring out how to better flag these at the
point(s) of origin might help a lot with reporting useful errors.

On 2019-05-02 10:20 a.m., Martin Maechler wrote:
>>>>>> Ben Bolker 
>>>>>>     on Wed, 1 May 2019 15:40:44 -0400 writes:
> 
>     > On 2019-04-29 8:09 p.m., DESPINA MICHAILIDOU wrote:
>     >> I am trying to run the following analysis and receive the following output
>     >> 
>     >> glmm_Comb_PH_tod <- glmer(Comb_PH_tod~ CA_effect + (1 | ID/SCAN_DATE/Side),
>     >> 			      data=TAK_data, family=binomial(link = "logit"))
> 
> what happens if you (Despina Michailidou) add  'verbose = 2,'
> in the above call to glmer() ?
> 
> You should get output which may help us to help you ..
> 
> (Note to lme4 maintainers: I'm working at improving our help
>  pages so people are less likely to *not* notice the 'verbose' argument.)
> 
> Best,
> Martin Maechler
> ETH Zurich
> 
>     >> summary(glmm_Comb_PH_tod)
>     >> 
>     >> Output
>     >> Error in length(value <- as.numeric(value)) == 1L :
>     >> (maxstephalfit) PIRLS step-halvings failed to reduce deviance in
>     >> pwrssUpdate
>     >>> summary(glmm_Comb_PH_tod)
>     >> Error in summary(glmm_Comb_PH_tod) : object 'glmm_Comb_PH_tod' not found
>     >> 
>     >> How can I fix that? Any suggestions? I am very new to R.
>     >> 
>     >> Thank you in advance.
>     >> Despina
> 
>     > The second error is relatively easy to understand; since your first
>     > command (using glmer(...)) didn't work, no object "glmm_Comb_PH_tod" has
>     > been created for you to summarize.
> 
>     > The first part is harder.  My guess would be that there's complete
>     > separation ; I've added a few more notes about the "PIRLS step-halving"
>     > error to the GLMM FAQ
>     > <http://bbolker.github.io/mixedmodels-misc/glmmFAQ.html>.  But it's hard
>     > to know without seeing the actual data.
> 
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