R - glmer different results on different machines (non-deterministic)
<p>Is there any reason why the <code>glmer</code> function from <code>lme4</code> would produce different results on different machines? The hardware in the machines are substantially different, though are all running the same OS, R and package versions <em>(turns out this is not actually true)</em>.</p>

<p>The formula has a grouped binomial response variable and 22 continuous fixed effects which are all on the same scale and several random effects, which are strings and I am using the <code>logit</code> link function.</p>

<pre><code>cbind(ill, not_ill) ~ 0 + fix1 + fix2 + ... + fix22 + (1|id/region/country) +
(1|season)
</code></pre>

<p>When using a train and test data set for leave one out cross validation, I get <strong>very</strong> similar results. However on one machine I get consistently clean output with no warnings; on another I get convergence warnings on every fold of the test.</p>

<p><strong><em>N.B. The train/test sets are identical across machines</em></strong></p>

<p>EDIT: adding <code>sessionInfo()</code></p>

<p><strong>Machine 1</strong> (this is the one that puts out nice results</p>

<pre><code>R version 3.3.1 (2016-06-21)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.1 LTS

locale:
 [1] LC_CTYPE=en_GB.UTF-8       LC_NUMERIC=C
 [3] LC_TIME=en_GB.UTF-8        LC_COLLATE=en_GB.UTF-8
 [5] LC_MONETARY=en_GB.UTF-8    LC_MESSAGES=en_GB.UTF-8
 [7] LC_PAPER=en_GB.UTF-8       LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_GB.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] blmeco_1.1     arm_1.9-1      MASS_7.3-45    lme4_1.1-12    Matrix_1.2-7.1

loaded via a namespace (and not attached):
 [1] minqa_1.2.4     coda_0.18-1     abind_1.4-5     Rcpp_0.12.7
 [5] MuMIn_1.15.6    splines_3.3.1   nlme_3.1-128    grid_3.3.1
 [9] nloptr_1.0.4    stats4_3.3.1    lattice_0.20-34
</code></pre>

<p><strong>Machine 2</strong> (Not so nice results)</p>

<pre><code>R version 3.2.3 (2015-12-10)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.1 LTS

locale:
 [1] LC_CTYPE=en_GB.UTF-8       LC_NUMERIC=C
 [3] LC_TIME=en_GB.UTF-8        LC_COLLATE=en_GB.UTF-8
 [5] LC_MONETARY=en_GB.UTF-8    LC_MESSAGES=en_GB.UTF-8
 [7] LC_PAPER=en_GB.UTF-8       LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_GB.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] blmeco_1.1   arm_1.9-1    MASS_7.3-45  lme4_1.1-12  Matrix_1.2-3

loaded via a namespace (and not attached):
 [1] minqa_1.2.4     coda_0.18-1     abind_1.4-5     Rcpp_0.12.7
 [5] MuMIn_1.15.6    splines_3.2.3   nlme_3.1-124    grid_3.2.3
 [9] nloptr_1.0.4    stats4_3.2.3    lattice_0.20-33
</code></pre>

<p>Obviously there's a few differences here that I missed so I will rectify that and see if there are any changes in output. Of the differences that exist, <code>Matrix</code> is the one most likely to be causing an issue as (I think) it's a dependency of <code>lme4</code>. Thanks for comments that led me here.</p>