I noticed a trend 5 years ago when I first started playing around with this scale. And that it seems that the higher you are on P, N, or both, the lower you are on E. It's like the energy can only go in so many directions at the same time.
Cross plot of data so far (not enough to test means for WP people, but enough to plot with - I'm including other data here, too, not just WP):
See how there's nothing in the top right corner on the bottom chart? Ooooh, stuff like this gets me so excited!
It's on this page on my website (yes, digging for hits!) - scroll down a bit:
EPQR crossplots writeup
Okay, enough geek stuff for now. Go back to your regularly scheduled programming.