by ManfromMiddletown, Wed Dec 20, 2006 at 04:49:46 PM EST
I loathe when I hear Democrats dismiss candidate's chances in a district citing the Cook PVI (Partisan Voting Index). The Cook PVI systematically and severely understimates base Democratic performane in rural areas. For too long, the blogosphere has been beholden to the bias created as an artifact of the manner in which the Cook Report operationalizes partisanship. First let's take a look at how the Cook PVI is constructed.
The index for each congressional district is derived by averaging the presidential election results in that district from the prior two elections, then comparing them to how the nation voted as a whole. The index indicates the more successful political party and how many percentage points higher than the national average for that party. It is published as a Letter+Number combination.
So the basis by which the Cook PVI determines partisanship for Congressional races is by using Presidential vote. The results of this are highly detrimental Democrats running in rural areas, because it makes what is often an entirely winnable district look impossible. Let's look at how Ohio looks if you use presidential vote as a measure of partisanship.