search

davidwhogg / LensTractor

finding strong gravitationally lensed quasars in ground-based data
GNU General Public License v2.0
5 stars 4 forks source link

Alternatives to BIC when high quality priors are used? #51

Open aagnello opened 9 years ago

aagnello commented 9 years ago

BIC just counts parameters: when we go to the trouble of including all teh information in the OM10 lens parameter prior, we're going to want to use a better approximation of the evidence. I suggest we look into the mean log likelihood over the posterior samples. This is a blunt tool, but hopefully sharp enough for our purposes. Note the need for samples, though.

drphilmarshall commented 9 years ago

We might consider the mean log likelihood as a better approximation to the Bayesian evidence. It differs by the information gain between prior and posterior - I'm not sure how much of the "Occam factor" is contained within this information term, but if both Nebula and Lens are capturing similar amounts of information, the mean log L might be useful in approximating the class probabilities.

drphilmarshall commented 9 years ago

@aagnello You also had an idea for some sort of weighted BIC, which in the spirit of finding engineering solutions might be thrown into a score comparison.