Am 22.05.2018 um 12:56 schrieb P-M:
I am sampling the posterior distribution in order to carry out some model selection (much like outlined in the cookbook). Interestingly both the Bethe as well as the mean field approximations of the posterior entropy appear to be returning an answer of 0.0. I was thus after some opinions: Are there cases where I might reasonably expect this to be the correct answer/how would people check that it is not simply being caused by the approximations not being applicable to my data set?
Differently from Bethe, the MF approximation can only return zero if the true entropy is also zero. This means that the posterior distribution is concentrated around a single partition with probability one, and others with probability zero. This should only occur if the SBM is a perfect fit, e.g. for very dense networks sampled from the SBM ensemble. For real data this should almost never happen. Best, Tiago -- Tiago de Paula Peixoto <tiago@skewed.de>