A Primer on Outlier Polls

Sometimes a single poll diverges from the pack of results generated by everyone else. How can you tell when the pollster is doing a better job of picking up a new trend versus simply being wrong?

Peter Kellner offers an educative account of how these events occur, using as an example a poll that shows two political parties in a neck and neck race while everyone poll has one party ahead. It’s a UK example, but that doesn’t matter, the value of the essay is its discussion of how to weigh poll respondents who say they have no preference, how small samples affect conclusions and the like.

The article is worth reading both for its clarity and its modesty. Kellner’s own polling firm disagrees with the outlier poll, but he remains balanced and gentlemanly throughout his critique.

Author: Keith Humphreys

Keith Humphreys is the Esther Ting Memorial Professor of Psychiatry at Stanford University and an Honorary Professor of Psychiatry at Kings College Lonon. His research, teaching and writing have focused on addictive disorders, self-help organizations (e.g., breast cancer support groups, Alcoholics Anonymous), evaluation research methods, and public policy related to health care, mental illness, veterans, drugs, crime and correctional systems. Professor Humphreys' over 300 scholarly articles, monographs and books have been cited over ten thousand times by scientific colleagues. He is a regular contributor to Washington Post and has also written for the New York Times, Wall Street Journal, Washington Monthly, San Francisco Chronicle, The Guardian (UK), The Telegraph (UK), Times Higher Education (UK), Crossbow (UK) and other media outlets.