Washington Post pollster Jon Cohen — best in the business! — penned an important and insightful piece for the Outlook section over the weekend in which he described five common myths associated with political polling.
You can — and should – read the entire piece. Below we give you each myth and the key line from Cohen’s writeup of them.
To the myths!
1. A campaign’s internal polls are more accurate than public polls. Cohen: “Most campaign surveys are presented with a heavy dose of spin. The goals are also different, with a premium on testing messages and anticipating the effects of strategic decisions, often with tenuous assumptions about ‘likely voters’ that may prove wrong.”
2. Polls prove that the first presidential debate upended the race. Cohen: “There is little evidence that the debate decisively moved the needle in key swing states. In six state surveys released Thursday by two well-regarded polling partnerships — NBC-Wall Street Journal-Marist and CBS-New York Times-Quinnipiac — there were virtually no shifts for either candidate compared with pre-debate polls.”
3. The best polls are those that correctly predict an election’s outcome. Cohen: “Getting elections ‘right’ is a necessary but insufficient reason to put great stock in polls. Some surveys could be well-modeled — adjusted to previous elections or to hunches, including, some surmise, tweaks to agree with other polls. (Few pollsters relish being an outlier.)”
4. Polls are skewed if they don’t interview equal numbers of Democrats and Republicans. Cohen: “Artificially evening out a poll’s partisan balance or arbitrarily setting it to match someone’s guess at turnout on Election Day may make one side a bit happier — but at the expense of distorting the current state of play.”
5. News outlets are biased in presenting polls favorable toward President Obama. Cohen: “In truth, news organizations have only one bias — toward news. Nothing demonstrates this better than the recent coverage of the Pew Research Center’s post-debate national poll, which showed big, across-the-board movements from Obama toward Romney. The Washington Post splashed the poll on its front page, and the survey provided days of fodder for cable news, illustrating that the media gravitate toward a competitive race, big shifts and conflict much more than one political party or the other.”