Friday, June 04, 2004

Margin of Error

A few of you noted in the CBS poll referenced below, the sample size of veterans in the poll is only 170. This means that the margin of error in the poll is +/- 8.6 for a standard 95% level of confidence. For the difference in the poll numbers to be statistically significant they therefore have to differ by about 17 percentage points.

Anyway, I don't think this is the sign of evil bias, just statistical stupidity. This is a standard error made by news organizations reporting on the poll results of subsamples.

...oops, that should be more like +/-7.5 and 15. What I get for trusting an unknown online MOE calculator...