I noticed a recent arXival describing an ABC approach to inferring halo modal parameters from lensing substructure, which it seems is the third in a series of installments, each of which churlishly manages to pretend not to be aware of my seminal ‘ABC for astronomy‘ paper from back in 2012. While I’m glad to see the ABC technique increasingly being used, consciously, for astronomical analyses, it does seem weird that having figured out that your technique fits within the ABC framework, not to learn from the statistical literature on that topic. Why I assume no learning has taken place is because the authors in this case haven’t moved beyond simple rejection ABC, which is a massive waste of computational power relative to even a basic population Monte Carlo approach. Moreover, it seems their scheme is consequently so inefficient that they cannot fit all of their lenses jointly, instead having to rely on some kind of multiplication of KDE approximations to each subset posterior to form the final posterior.
Heck, if they’d read into the problem from a statistical point of view they might even have learned a bit about how to do subset posteriors better. For instance, they write that the multiplication of these sub-posteriors is only possible if you use uniform priors, and consequently they go to a lot of trouble to choose transformations allowing for construction of entirely uniform priors. But, wait for it, what about this from consensus MC: ?!