Reading a Poll

A poll report is read by checking four numbers and one sentence: margin of error, dates, respondent count, population sampled, and the question itself.

Take a report: Candidate A 51 percent, Candidate B 49, one thousand likely voters, margin of error three points, fielded last week. Step one — dates: recent, usable. Step two — respondents and population: one thousand likely voters is a standard scientific sample. Step three — the question: named candidates, neutral wording, no lead-in. Step four — the margin: apply three points both ways; A's interval runs 48 to 54, B's runs 46 to 52. The intervals overlap, so the poll supports "close race," not "A leads." Now a second report: a candidate at 43 percent with an 8-point margin — an interval from 35 to 51. A sixteen-point window predicts almost nothing; the margin is far too high, and the poll cannot carry a conclusion.