Lots of answers about apples-to-applesness, and such, but from a very practical viewpoint, the "said activities" part of "participating in said activities" is h

Lots of answers about apples-to-applesness, and such, but from a very practical viewpoint, the "said activities" part of "participating in said activities" is hard to define and measure. Should you condition on swimming, swimming in the ocean, swimming in the ocean in california, swimming in the ocean in the Santa Cruz area, or swimming in the ocean at Año Nuevo (or even some part of that beach)? However you decide to break it down, do you even have that data? In stats, lots of questions begin and end with "do you have data on that?"