This study shows a north-south gradient in France for CD but not for UC.

Abstract:Generalized linear models with a Poisson distribution are often used to model cancer registry data stratified by sex, age, year, and little geographical units. We compare three different approaches which take into account possible spatial correlation among neighbouring units, using lung cancer incidence data. Inference is fully Bayesian and uses Markov Chain Monte Carlo techniques. Comparison between models is based on the Deviance Information Criterion (DIC).