Opinion: Dueling, confusing polls in the Barack Obama/Hillary Clinton race
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Somebody’s survey sample is all fouled up. Or maybe we just need periodic reminders of how imprecise efforts to gauge public opinion can be.
Two national surveys by esteemed polling organizations -- each conducted over precisely the same time period, Thursday through Sunday -- were released today, and the results, at first glance, significantly differ.
A CBS News/New York Times poll found that among those who have voted or plan to cast ballots in a Democratic presidential primary, Barack Obama leads Hillary Clinton, 50% to 38%.
By contrast, a USA Today/Gallup poll of Democratic voters put Clinton ahead, 51% to 44%.
Baffled? Wait, it gets murkier.
The New York Times story on the survey it co-commissioned takes an arm’s-length attitude toward the Democratic horse race question, focusing on other findings instead. It contains this caveat in the seventh paragraph: ‘The relatively small number of Democrats surveyed limits the conclusions that can be drawn about the poll’s findings regarding sentiment in the party.’
In fact, nowhere in the story ...
... are the figures revealed for the Democratic matchup (which was based on interviews with 283 likely voters and has an error margin of plus or minus 6 percentage points).
The CBS News story on the poll did not show similar restraint. It gives the horse race numbers in the third paragraph, noting that they show that Obama’s lead had risen to 12 percentage points from 8 in a comparable survey conducted less than a week ago.
The USA Today/Gallup poll interviewed a larger sample of Democratic and Democratic-leaning independents -- 516, giving its result on the Clinton-Obama preferences an error margin of plus or minus 5 percentage points.
Still, caveats abound, as the latter part of the USA Today story delineates.
The article notes that the survey it spotlights differs ‘from a separate Gallup tracking poll of voters, which shows Obama with a narrow lead, 49%-45%.’
This tracking poll (available here) not only was based on a larger sample, putting its error margin at plus or minus 3 percentage points, but it is more up to date, with more interviews conducted on Saturday.
Bottom line: Poll readers beware.
-- Don Frederick