[R-sig-ME] Nest survival: (maxstephalfit) PIRLS step-halvings failed to reduce deviance in pwrssUpdate

Ben Bolker bbolker at gmail.com
Thu Mar 5 04:11:17 CET 2015

Elwyn Sharps <e.sharps at ...> writes:



> I am using a nest survival model (glmer) with random effects and a logistic
> exposure link function, as described here:
> http://stackoverflow.com/questions/19012128/user-defined-link-function-for-
> glmer-for-known-fate-survival-modelling
> I am running a number of different models, with varying fixed effects. Some
> of them are running well, with no error or warning messages, however
> for other models, I am getting the following message:
> *Error: (maxstephalfit) PIRLS step-halvings failed to reduce deviance in
> pwrssUpdate*
> I'm not sure what is causing this error. I have tried to check the data for
> simple problems, however can't see anything that could be causing trouble.
> I've also tried running the model without the random effects. This results
> in a different error message:
> *Error: cannot find valid starting values: please specify some*

  Example data doesn't seem to be attached: it may have been
stripped by the mailing list software.  Can you post it somewhere
public and provide a URL?

  My guess it that there is something rather wonky about the data
for this example, e.g. complete separation (for example, no individuals
die for some combination of predictor variables).  Hard to say
without the data though.

  Ben Bolker

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