Large variance and SD for random effects
Dear Paul, Your random effect structure looks quite complicated. Maybe too complex for the data. Your model is very likely suffering from (quasi) complete separation. Besides the large variances, you should also be alarmed by the near perfect correlations among some random effects. Best regards, ir. Thierry Onkelinx Statisticus / Statistician Vlaamse Overheid / Government of Flanders INSTITUUT VOOR NATUUR- EN BOSONDERZOEK / RESEARCH INSTITUTE FOR NATURE AND FOREST Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance thierry.onkelinx at inbo.be Havenlaan 88 bus 73, 1000 Brussel www.inbo.be /////////////////////////////////////////////////////////////////////////////////////////// To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey /////////////////////////////////////////////////////////////////////////////////////////// <https://www.inbo.be> 2018-03-05 20:24 GMT+01:00 cumuluss <cumuluss at gmx.de>:
Hello, the result of my GLMM with binomial error structure revealed for one of the random intercepts and slopes variances and Sd's larger then 1
Generalized linear mixed model fit by maximum likelihood (Laplace
Approximation) ['glmerMod']
Family: binomial ( logit )
Formula: obs.yn ~ z.lengthxyz + z.obsX + Spe_tr_subspecie + (1 | commu) +
(1 + z.lengthxyz + z.obsX | Siteun) + (1 + z.lengthxyz +
z.obsX + Spe_tr_subspecie_a.c + Spe_tr_subspecie_b.c +
Spe_tr_subspecie_c.c | behavior)
Random effects:
Groups Name Variance Std.Dev. Corr
commu (Intercept) 0.614004 0.78358
Siteun (Intercept) 0.521198 0.72194
z.lengthxyz 0.001016 0.03188 1.00
z.obsX 0.306931 0.55401 -0.17 -0.19
behavior (Intercept) 2.966139 1.72225
z.lengthxyz 0.030171 0.17370 0.77
z.obsX 0.412169 0.64200 0.20 -0.36
Spe_tr_subspecie_a.c 1.853903 1.36158 0.58 0.62 0.11
Spe_tr_subspecie_b.c 3.973439 1.99335 0.51 0.23 0.25 0.65
Spe_tr_subspecie_c.c 7.401343 2.72054 0.39 0.30 0.47
0.79 0.60
Number of obs: 4413, groups: commu, 144; Siteun, 108; behavior, 31
Now I wonder, whether that is a reason to worry, that the result could be not valid? Thanks in advance for any comments! Paul
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