[R] Mac/PC differences in lmer results

Nicolas Schuck n|co@@chuck @end|ng |rom gm@||@com
Wed Jun 5 12:15:53 CEST 2019

bert: you are right, sorry for not cc-ing the list. thanks also for the hint. 

I wanted to bring this up here again, emphasising that we do find in at least one case *a very large difference* in the p value, using the same scripts and data on a windows versus mac machine (see reproducible example in the gitlab link posted below). I have now come across several instances in which results of (g)lmer models don’t agree on windows vs unix-based machines, which I find a bit disturbing. any ideas where non-negligible differences could come from? 


> On 30. May 2019, at 16:58, Bert Gunter <bgunter.4567 using gmail.com> wrote:
> Unless there us good reason not to, always cc the list. I have done so here.
> The R Installation manual has some info on how to use different BLASes I believe, but someone with expertise (I have none) needs to respond to your queries.
> On Thu, May 30, 2019 at 7:50 AM Nicolas Schuck <nico.schuck using gmail.com <mailto:nico.schuck using gmail.com>> wrote:
> I know that it is in use on the Mac, see sessionInfo below. I have to check on the Win system. Why would that make such a difference and how could I make the Win get the same results as the Unix Systems? 
> R version 3.6.0 (2019-04-26) 
> Platform: x86_64-apple-darwin15.6.0 (64-bit) 
> Running under: macOS Mojave 10.14.5 
> Matrix products: default 
> BLAS:  /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRblas.0.dylib 
> LAPACK: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRlapack.dylib 
> Random number generation: 
> RNG:  Mersenne-Twister 
> Normal:  Inversion Sample:  Rounding 
> locale: [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8 
> attached base packages: [1] stats  graphics  grDevices utils  datasets  methods  base 
> Thanks, Nico 
> On 30. May 2019, at 16:34, Bert Gunter <bgunter.4567 using gmail.com <mailto:bgunter.4567 using gmail.com>> wrote:
>> The BLAS in use on each?
>> Bert Gunter
>> "The trouble with having an open mind is that people keep coming along and sticking things into it."
>> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
>> On Thu, May 30, 2019 at 5:27 AM Nicolas Schuck <nico.schuck using gmail.com <mailto:nico.schuck using gmail.com>> wrote:
>> Dear fellow R coders, 
>> I am observing differences in results obtained using glmer when using a Mac or Linux computer versus a PC. Specifically, I am talking about a relatively complex glmer model with a nested random effects structure. The model is set up in the following way: 
>> gcctrl = glmerControl(optimizer=c('nloptwrap'), optCtrl = list(maxfun = 500000), calc.derivs = FALSE)
>> glmer_pre_instr1 = glmer(
>>       formula = cbind(FREQ, NSAMP-FREQ) ~ FDIST_minz + poly(RFREQ,2) + ROI + (1 + FDIST_minz + RFREQ + ROI|ID/COL), 
>>       data = cdf_pre_instr, 
>>       family = binomial, 
>>       control = gcctrl)
>> Code and data of an example for which I find reproducible, non-negligible differences between Mac/Win can be found here: https://gitlab.com/nschuck/glmer_sandbox/tree/master <https://gitlab.com/nschuck/glmer_sandbox/tree/master> <https://gitlab.com/nschuck/glmer_sandbox/tree/master <https://gitlab.com/nschuck/glmer_sandbox/tree/master>>
>> The differences between the fitted models seem to be most pronounced regarding the estimated correlation structure of the random effects terms. Mac and Linux yield very similar results, but Windows deviates quite a bit in some cases. This has a large impact on p values obtained when performing model comparisons. I have tried this on Mac OS 10.14, Windows 10 and Ubuntu and Debian. All systems I have tried are using lme 1.1.21 and R 3.5+. 
>> Does anyone have an idea what the underlying cause might be? 
>> Thanks, 
>> Nico 
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