The Cook Partisan Voting Index or the Cook PVI: https://en.wikipedia.org/wiki/Cook_Partisan_Voting_Index
I’ll be using this in conjunction with my formula:
Initiative + Prone to Go Republican or Democratic (by state) = outcome?
My formula I + P^R or I + P^D = Outcome? (O?)
The Freelance Voter Probability & Initiative Index
or simply “The Freelance VPII” or “The Freelance VPI2”