PBI or Party Brand Index is a concept I developed (with some much appreciated help from pl515) as a replacement for PVI. PVI (Partisan Voting Index), which is measured by averaging the percentage of the vote from the last two presidential elections in each house district, and comparing it to the nation as a whole, is a useful shorthand for understanding the liberal v. conservative dynamics of a district. But PVI in my opinion it falls short in a number of areas. First it doesn't explain states like Arkansas or West Virginia. These states have districts who's PVIs indicates a Democrat shouldn't win, yet Democrats (outside of the presidency) win quite handily. Secondly why is this the case in Arkansas but not Oklahoma with similar PVI rated districts?
Lastly PVI can miss trends as it takes 4 years to readjust. The purpose of Party Brand Index is to give a better idea of how a candidate does not relative to how the presidential candidate did, but compared to how their generic PARTY should be expected to perform. I've tackled IN, NC, CO, VA, MO, OK, AR, WV, NH, OH, and Florida. Now I will look at the fast becoming a purple state of Arizona.
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