Friday, May 8, 2009

A 29 point drop in one month?

The Civitas Institute is proclaiming that Bev Perdue's net favorability rating has dropped 29 points in one month.

That's certainly startling, but in their discussion of why this might have occurred they skipped what I think is probably the biggest reason for this startling shift: they changed pollsters.

Civitas is often referred to as a polling company but it actually pays a vendor to conduct its polls, although they do most of the work on determining the content for the surveys.

Traditionally Civitas has used Tel Opinion Research for its surveys, but this month they switched to McLaughlin and Associates.

If there's one thing the week by week horse race polling showed during the 2008 election it was that different polling companies could ask the same questions and come up with very different answers.

I thought the favorability ratings Tel Opinion Research found for Bev Perdue in her first few months of office were extremely inflated. For instance last month they found 58% of North Carolinians holding a favorable opinion of Perdue while our poll in the field at an almost identical time found her approval rating at only 44%.

The numbers McLaughlin finds sound pretty reasonable to me- the 44% favorability rating they give her is very similar to our recent finding of a 41% approval rating.

But comparing the Tel Opinion numbers to the McLaughlin numbers as if they're the same thing is not valid, even if both polls were commissioned by Civitas. It's like comparing apples and oranges when they're conducted by two different companies. Perdue's standing has probably declined in the last month and if the economy doesn't turn around it may continue to drop but she's not plummeting at nearly the rate they are claiming.

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