Inclusion of level-one variable increases group level variance in a multilevel negative binomial regression
Posted: Wed Aug 25, 2021 2:14 pm
Hi,
I am running a multilevel negative binomial regression predicting the number of crimes a student commits in a year in school.
In the empty model the variance associated with the random intercept is virtually 0 and tests suggest that this model is not a better fit than a single level model.
When I include an individual level predictor (crime propensity), which is strongly and positively associated with crime, the group level variance increases and tests suggest that the multilevel model is a better fit than the individual model.
Descriptive analysis of my data shows that there are higher levels of criminal behaviour in schools where pupils have higher levels of crime propensity and so I would expect there to be some variance associated with the random intercept in the empty model, which reduces once propensity is added to the model.
As such, I am struggling to interpret these results both statistically and substantively and would appreciate any thoughts on possible interpretations.
Thanks in advanced,
Liam
I am running a multilevel negative binomial regression predicting the number of crimes a student commits in a year in school.
In the empty model the variance associated with the random intercept is virtually 0 and tests suggest that this model is not a better fit than a single level model.
When I include an individual level predictor (crime propensity), which is strongly and positively associated with crime, the group level variance increases and tests suggest that the multilevel model is a better fit than the individual model.
Descriptive analysis of my data shows that there are higher levels of criminal behaviour in schools where pupils have higher levels of crime propensity and so I would expect there to be some variance associated with the random intercept in the empty model, which reduces once propensity is added to the model.
As such, I am struggling to interpret these results both statistically and substantively and would appreciate any thoughts on possible interpretations.
Thanks in advanced,
Liam