DPR clarification

A small contribution to a substantial app. I hope you like it. I'm tempted to put the "very roughly..." analogy part before the details.

The aim is to make these stats clearer and complete enough for the wide range of people that'll use this app. I ran this text by 2 people and made adjustments. That's not a very big usability test.

(Anyway, now that FIRST has figured out how to really reward teamwork, the linearity assumption isn't great.)