“Markey’s lead over Gomez shrinks” claime the Boston Globe. “A new poll from Suffolk University suggests that we could have another close special election for a Senate seat in Massachusetts on our hands,” hypes the Washington Post.
But is the latest Suffolk University poll truly signal? Or is it noise? Is this the start of another 2010-like trend? Or do these media reports show that journalists haven’t learned that polls move up and down during the course of a campaign season and such fluctuations aren’t necessarily statistically significant?
If you haven’t seen it yet, the Suffolk poll released today shows Markey ahead of Gomez by 7 points, 48-41. Yes, that’s a major decline from the prior Suffolk poll — but, I don’t think any of us really believed that previous poll showing Markey up by 17. Bad comparison. How does it stack up with the other independent polls of late? Well, today’s poll remains within margin-of-error range of every other independent poll since the beginning of May.
Nate Silver hasn’t weighed in on this race since May 6, but at that time Silver said that Republicans “can win Congressional elections in blue states if just about everything goes right. . . . However these instances are rare. Mr. Gomez is capable of winning, but his roughly five-point deficit to Mr. Markey in the polls now could also prove to be a high-water mark.” Gomez’s deficit has still exceeded 5 points in every independent poll since.
So right now, I’m calling this latest change in Suffolk polling results noise, not signal. I’d need to see more data with a considerably more significant downward trend before I’m ready to declare signal.