[R-sig-ME] glmer() Gamma distribution - constant coefficient of variation

[Hedyeh Ahmadi]

Hi all,
I am running a glmer() with Gamma distribution and identity link. The R output is as follows. I would like to check the constant coefficient of variation assumption in R but I am not sure where to start. Any help would be appreciated.

Generalized linear mixed model fit by maximum likelihood (Laplace Approximation) ['glmerMod']
 Family: Gamma  ( identity )
Formula: Y ~ 1 + pm252016aa + race +prnt.empl + overall.income +  (1 | site)
Data: Family
Control: glmerControl(optimizer = "bobyqa", optCtrl = list(maxfun = 100000))

     AIC       BIC           logLik           deviance df.resid
 68781.7   68917.1 -34371.8     68743.7     9180

Scaled residuals:
    Min      1Q             Median      3Q        Max
-1.9286   -0.7314   -0.0598    0.6770    3.9599

Random effects:
 Groups    Name               Variance   Std.Dev.
 site (Intercept)      0.66157    0.8134
 Residual                            0.04502     0.2122
Number of obs: 9199,  groups:  site, 21

Fixed effects:
                                                               Estimate     Std. Error         t value             Pr(>|z|)
(Intercept)                                              52.3578               1.3102            39.962         < 0.0000000000000002 ***
pm252016aa                                         -0.1260                 0.1099           -1.147            0.251212
race_1                                                     1.0913                  0.7106         -1.536             0.124628
race_2                                                     -1.1787                  0.6870          3.171             0.001518 **
prnt.empl                                               2.8852                  0.4377            4.307            0.000016517 **
overall.income[>=100K]                      -1.8476                 0.3693          -5.003            0.000000566 ***
overall.income[>=50K & <100K]        -0.8644                0.3403             -2.540            0.011078 *
---
Signif. codes:  0 �***� 0.001 �**� 0.01 �*� 0.05 �.� 0.1 � � 1


Best,

Hedyeh Ahmadi, Ph.D.
Statistician
Keck School of Medicine
Department of Preventive Medicine
University of Southern California

Postdoctoral Scholar
Institute for Interdisciplinary Salivary Bioscience Research (IISBR)
University of California, Irvine

LinkedIn
www.linkedin.com/in/hedyeh-ahmadi<http://www.linkedin.com/in/hedyeh-ahmadi>
<http://www.linkedin.com/in/hedyeh-ahmadi><http://www.linkedin.com/in/hedyeh-ahmadi>





	[[alternative HTML version deleted]]