Table 2 Parameters of multilevel and single level negative binomial regression

Parameters of the random intercept only model of the multilevel negative binomial regression

Region level variance (95%CI)

0.475(0.030,7.695)

Median incident rate ratio (95% CI)

3.748(3.671,3.827)

AIC

26075.32

BIC

26095.22

Log likelihood

-13034.658

Information criteria and the overdispersion test of the multivariable single level negative binomial regression

Information criteria

Multivariable Negative binomial Regression

AIC

20943.72

BIC

21145.86

Log likelyhood test of α = 0

Log Chi2(01) = 42.07, p value < 0.001