Thursday, July 8, 2010

PVI breakdown by county

As part of a continuing effort to generate some objective tools for better understanding and analyzing the politics of the state I've created a county level PVI index, what I'm calling hPVI. For those of you unfamiliar with PVI, it's a tool created by The Cook Political Report for evaluating the partisan makeup of congressional districts.

In formulating a congressional district's PVI, the results of the last two presidential elections are used. But should that be what we use for formulating a county's PVI? The whole point of this exercise is to get a better idea of the partisan makeup of the state at a local level; in that case would the results of the last two gubernatorial elections be a better way to go? How about a hybrid of the two, using the last presidential election and the last gubernatorial election? What about Senate races, should those be included?

In the end I went with the hybrid method and did not include Senate races, this means the county level PVI is arrived at by averaging the Democratic vote share of the 2008 Presidential election and the 2006 gubernatorial election and subtracting from that the average of the Republican vote share in those two races. This is than compared with how the state voted to arrive at the county level PVI, or what I'm calling hPVI.

So for example, in Beltrami county the average Democratic vote share for 2008 and 2006 was 52.5% and the average Republican vote share was 43.4%, when you subtract the GOP average from the Democratic average you get 9.1, when you than subtract the PVI of the state as a whole (with this method it's 5) you get 4.1, for an hPVI of 4 (PVI is rounded to the nearest whole number).

Here are the top 5 most Democratic counties according to hPVI:

Here are the top five most GOP counties:

Keep in mind that the hPVI is telling you how Democratic or Republican a county is compared to the state as a whole. Since Minnesota itself has a hPVI of 5, a county with a -1 hPVI is 1 point more Republican than the state, but is still a baseline D+4 county.


Here's the complete list:

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