This morning was a "hack session" in the Josh-Peek-organized reading group on astrostatistics up at Columbia called #NYCastroML. I helped Kelle Cruz (CUNY) and others build a mixture-of-Gaussians model of the WISE point-source catalog. Well, we just worked on single-Gaussian models, but we are getting ready to do multiple Gaussians. We got a long way, although, as usual, most of the session was really "data munging" and not "data analysis". That's not uncommon: Getting the data into a consistent, useful, checked state is often the hardest part of the project. And, as far as I know, there is no "theory" of this part of data analysis. It just is.