Innumerate, and proud of it

Why does Howard Kurtz still have a job? I don’t suppose being pig-ignorant of basic statistics is a firing offense, but “standing by” your false assertion when someone who knows what he’s talking about tries to correct you ought to be.

Ladies and gentlemen, Mr. Howard Kurtz:

Gainesville, Va.: Howard, I think it is time to send political reporters and commentators to a remedial course in statistics. You wrote that Obama could as easily be tied with Hillary because his lead of 28 percent to 25 percent is within the margin of error. What the confidence interval means is that if the confidence interval is smaller than the difference between two means we can be 95 percent (not 100 percent) sure that the opinions held in the universe will reflect the higher response to be greater than the lower. If the difference of the two poll results are within the confidence interval, it may mean we can only be sure that one is greater than the other with 80 percent or 75 percent confidence. It doesn’t mean they are tied. It really would be helpful if you and your colleagues boned up on this question before you made statements that aren’t true.

Howard Kurtz: I stand by what I said. Obama’s lead is within the margin of error. In fact, the poll’s margin of error was over 4 percent, which makes the 3-point lead even more of what I would regard as a statistical tie.

Does Kurtz really believe that this is a matter of opinion, rather than a question answerable (and answered) by mathematics? Or has he just adopted as his motto, “Never apologize, never explain”?

Of course, since the reported “margin of error” is only the margin of sampling error, ignoring all the other ways a poll sample can fail to reflect the universe from which it is supposed to have been drawn, it’s not really true that we’re 80% confident that Obama is ahead of HRC. But a 3% spread still isn’t a tie.

Author: Mark Kleiman

Professor of Public Policy at the NYU Marron Institute for Urban Management and editor of the Journal of Drug Policy Analysis. Teaches about the methods of policy analysis about drug abuse control and crime control policy, working out the implications of two principles: that swift and certain sanctions don't have to be severe to be effective, and that well-designed threats usually don't have to be carried out. Books: Drugs and Drug Policy: What Everyone Needs to Know (with Jonathan Caulkins and Angela Hawken) When Brute Force Fails: How to Have Less Crime and Less Punishment (Princeton, 2009; named one of the "books of the year" by The Economist Against Excess: Drug Policy for Results (Basic, 1993) Marijuana: Costs of Abuse, Costs of Control (Greenwood, 1989) UCLA Homepage Curriculum Vitae Contact: