Test for dispersion
library("AER")
```

```
dispersiontest(Model.poi,trafo=1)
Model.neg <- MASS::glm.nb(claim_nb ~ drv_age1 + drv_age2 + drv_drv2_r + pol_sit_duration
+ pol_bonus + pol_coverage_r + pol_payd_r + pol_usage_r
+ vh_fuel_r + vh_din + vh_age , data = DataTrain,
link = "log", na.action = na.omit)
odTest(Model.neg)