Peter Loewen considers the recent failures of political polling.
The problem is not with the first part. Pollsters have developed very clever ways to obtain people’s honest opinions. They can use live people on the phone. They can find respondents over the Internet. They can use “interactive voice recognition,” in which a poll is conducted via a pre-recorded phone message and respondents key in their answers. Data collection is more affordable than ever, and text messaging and smartphone apps are promising even swifter data collection.
The problem is the second part. Pollsters simply do not know enough about who responds to polls via some media, who replies through others, and what kinds of people ignore polling requests entirely. The problem isn’t getting sample, it’s getting good sample. Simply knowing a respondent’s demographic information is not enough to correct for bad sampling. The result is that we cannot extrapolate with sufficient accuracy from our samples to the whole population. We cannot, in other words, know with much confidence the likely outcome of an election before the votes are cast.