check_overdispersion {insurancerating} | R Documentation |
Check overdispersion of Poisson GLM
Description
Check Poisson GLM for overdispersion.
Usage
check_overdispersion(object)
Arguments
object |
fitted model of class |
Details
A dispersion ratio larger than one indicates overdispersion, this
occurs when the observed variance is higher than the variance of the
theoretical model. If the dispersion ratio is close to one, a Poisson model
fits well to the data. A p-value < .05 indicates overdispersion.
Overdispersion > 2 probably means there is a larger problem with the data:
check (again) for outliers, obvious lack of fit. Adopted from
performance::check_overdispersion()
.
Value
A list with dispersion ratio, chi-squared statistic, and p-value.
Author(s)
Martin Haringa
References
Bolker B et al. (2017): GLMM FAQ.
Examples
x <- glm(nclaims ~ area, offset = log(exposure), family = poisson(),
data = MTPL2)
check_overdispersion(x)
[Package insurancerating version 0.7.4 Index]