margin of error

PSA: Everything you know about the margin of error is wrong

February 27th, 2012 at 3:26 pm by under Nesi's Notes, On the Main Site

When our exclusive WPRI 12 poll drops at 6 p.m. tonight, you’ll see that the margin of error is plus or minus 4.38 percentage points for the entire poll and plus or minus 6.2 percentage points for the 1st District only.

Inevitably, some well-meaning folks will take our top-line results and then argue that anything in a range of, respectively, 8.76 points or 12.4 points could be true. If Cicilline is down 5 points, these folks may say the race is a “statistical tie.”

Those folks will be wrong, and here’s why, as explained by Kevin Drum back in 2008 (emphasis mine):