filtered stats.pearsonr subroutine

[tahorst]

Is it worth making a filtered-stats.pearsonr subroutine that other analysis classes might call in the future?

Possibly. I think I've run into this issue in other analysis scripts. I was surprised the pearsonr function doesn't have an arg to handle this when I looked at the docs.

Originally posted by @tahorst in #1209 (comment)