Quality polling can improve political journalism by keeping horserace stories honest, or  at least tethered to some reality.

Most of the time, poll data lead journalists to more accurate conclusions. In New Jersey, however, we witnessed the inversion of that process: The polls were bent to conform to the story journalists wanted to tell, even though it was largely unsupported by the data. (Full disclosure: Sen. Jon Corzine, the Democratic candidate for governor, is our client.)

In the closing days of the campaign, personal invective from the senator’s ex-wife appeared in the press and became the central thrust of Republican candidate Douglas Forrester’s ads. The story was too juicy for reporters to resist: a political campaign turned on its head by comments from a former spouse.

But instead of acting as a factual check on drooling reporters, polls were widely misinterpreted by their usually careful sponsors to support a theory that had little basis in fact.

Typical of the breathless reporting was a piece headlined: “Corzine falters as dirt flies,” which argued the “race looked set for a nail-biting finish yesterday with two new polls showing Sen. Jon Corzine paying a price for attack ads featuring his disgruntled ex-wife.”

The evidence?

First a Marist poll that, under the heading “What a difference a day makes,” offered this “analysis”: “The race has taken a decidedly different turn. On Wednesday, Jon Corzine had a comfortable lead of 13 points over Doug Forrester.