One reader emailed to take strong exception to my use of the word "misleading" in the following sentence from my column posted yesterday on NationalJournal.com:
One reason for the misleading early numbers in 2006 may have been that Quinnipiac sampled all self-identified registered Democrats rather than a narrower subset of likely primary voters. Their May 2006 sample of 528 Democrats, for example, amounted to 34 percent of the full sample of 1,536 registered voters they interviewed. Yet the actual Democratic primary turnout amounted to just 15 percent of Connecticut's active registered voters.
I will grant that I could have chosen a less loaded word than "misleading," as some will hear it as an insinuation about the pollster's motives or the accuracy of data. For the record, I do not believe that anyone involved in producing the Quinninpiac Poll meant to mislead anyone, and did not mean to imply that the data they reported were inaccurate. The record should show that once they shifted to reporting vote preferences among a narrower group of "likely voters," they showed Lamont running much closer to Lieberman in June, "inching ahead" in July and ultimately leading by a wide margin in early August. Their final poll showed Lamont leading by six percentage points. He won by four -- that's as close as any poll should expect to get.
The larger point I was trying to make with the column is that we mislead ourselves -- and by we I mean all of us, pollsters, journalists, campaigns, political junkies -- whenever we treat samples of a third to half of adults in a state as a meaningful measure of the preferences of "likely primary voters" when the actual turnout is typically a much smaller fraction of adults.
My use of the Quinnipiac Poll was also largely a coincidence. They happened to produce two polls last week with primary head-to-head questions, one in Connecticut, and a similarly designed poll in Connecticut three years ago. However, their practices in terms of sampling primary voters are very similar to those used by most other media pollsters.
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