Wednesday, June 16, 2010

Gubernatorial Polling Index

Now that there are a few polls out on the Governor's race we can create a composite index (G.P.I.) of them that can be updated as more polls come in. Here's what the polling index for the DFL primary looks like.

There have only been two polls done since the DFL nomination (I'm not going to use those from before), so for this race we have an average (Ave) and a weighted average (wAve). The weighted average is an average of all the polls, weighted against a variable called "weight". This variable represents a combination of the Pollster Rating and the age of the poll. The newer the poll and better the pollster the higher it will be weighted. The age of the poll has more effect on the weight then the pollster rating, with the age making up 75% of the weight and the Pollster Rating making up 25%. However the age weighting will essentially fall off at 50 days and this will get adjusted as we get closer to the race in question.

As you can see the weighted average doesn't really change the regular average too much in the DFL primary, this is because there are only two polls and their weights are not drastically different. Let's look at the overall polling in the race now.

Here we have a new type of average, the average of the three most recent polls conducted, similar to what RealClearPolitics does. We'll have to wait for a new poll to see if the upward movement shown by the Deicision Resources poll on the DFL side continues.


* The Mellman poll of the primary race was paid for by the DFL who has an endorsed candidate in the race.

** Decision Resources doesn't have a rating in the Pollster Ratings so they were assigned the Default/New Pollster rating. Additionally a firm that one of the candidates worked for is a client of the pollster.

*** For Tom Emmer and Tom Horner their numbers against all the DFL candidates were used.

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