. Author manuscript; available in PMC: 2013 Mar 1.

Published in final edited form as: Biom J. 2012 Mar;54(2):264–280. doi: 10.1002/bimj.201100041

Table 3.

Simulation results for modeling univariate count data. The estimates of three models are compared: NMM, the negative-binomial mixed model; PMM, the Poisson mixed model; LMM2, the normal linear mixed model with log transformation. The true parameters β₀ = 1, β₁ = 1.

Simulated data	n	m	Estimate	NMM		PMM		LMM2
				${\hat{β}}_{0}$	${\hat{β}}_{1}$	${\hat{β}}_{0}$	${\hat{β}}_{1}$	${\hat{β}}_{0}$	${\hat{β}}_{1}$
Negative binomial	10	10	Mean	1.008	0.997	0.980	0.995	0.922	0.863
			SD	0.371	0.309	0.401	0.368	0.319	0.296
			Mean( $\hat{s e}$ )	0.354	0.306	0.317	0.133	0.328	0.299
	50	25	Mean	0.998	1.004	0.986	1.003	0.908	0.872
			SD	0.149	0.085	0.155	0.117	0.126	0.085
			Mean( $\hat{s e}$ )	0.149	0.086	0.143	0.036	0.133	0.085
Poisson	10	10	Mean	0.986	0.997	0.986	0.996	1.068	0.923
			SD	0.335	0.138	0.335	0.137	0.310	0.187
			Mean( $\hat{s e}$ )	0.313	0.139	0.311	0.134	0.309	0.177
	50	25	Mean	0.988	1.002	0.987	1.002	1.064	0.931
			SD	0.141	0.038	0.142	0.037	0.128	0.054
			Mean( $\hat{s e}$ )	0.142	0.037	0.141	0.037	0.134	0.051