**A**n interesting confusion on X validated where someone was convinced that using the Bernoulli representation of a sequence of Bernoulli experiments led to different posterior probabilities of two possible models than when using their Binomial representation. The confusion actually stemmed from using different conditionals, namely N¹=4,N²=1 in the first case (for a model M¹ with two probabilities p¹ and p²) and N¹+N²=5 in the second case (for a model M² with a single probability p⁰). While (N¹,N²) is sufficient for the first model and N¹+N² is sufficient for the second model, P(M¹|N¹,N²) is not commensurable to P(M²|N¹+N²)! Another illustration of the fickleness of the notion of sufficiency when comparing models.

Bayesian model choice, Bayesian Statistics, Books, conditioning, cross validated, Statistics, sufficiency