Checking for overdispersion
In this exercise you will check for overdispersion in the model you fitted previously, namely the horseshoe crab Poisson model where you fitted sat
given width
. Recall from the video that to check for potential overdispersion in the fit you would compute the following
model.pearson_chi2 / model.df_resid
where .pearson_chi2
represents Pearson statistic and .df_resid
represents the degrees of freedom of the residuals.
The model crab_pois
and crab
dataset are preloaded in the workspace.
This exercise is part of the course
Generalized Linear Models in Python
Exercise instructions
- Compute the ratio of the Pearson statistic and the degrees of freedom of the residuals for the
crab_pois
Poisson regression model.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Compute and print the overdispersion approximation
____(____.____ / ____.____)