I published a paper that used statistical analysis earlier this year, including a series of calculations that were written up as what I'll call a big honking equation using sigma notation. I included the equation in the Materials & Methods section, with the only explanation being to state what each variable stood for. This approach is SOP, as far as I can tell.
I agree with the idea that a student should be able to explain how a method works (e.g. "Tell me Johnny, why can't we divide by zero?"). That said, one of my kids was a victim of EM for two years, and its approach is a long way from what I just described. It isn't what I'd call mathematically correct (but you know that already!).
