Refer to the previous exercise. Allow overdispersion by fitting the negative binomial loglinear model.

a. Report the prediction equation and the estimate of the dispersion parameter and its SE. Is there evidence that this model gives a better fit than the Poisson model?

b. Construct a 95% confidence interval for β. Compare it with the one in (c)

in the previous exercise. Interpret, and explain why the interval is wider with the negative binomial model.