Romney campaigned Thursday in Florida, where two nonpartisan live operator polls conducted over the past two weeks both indicate Obama has a five-point advantage, which is within the surveys' sampling errors.

CNN: SHARE THIS

The reason for this seemingly dotty result is that the errors from scientific sampling are easier to quantify (and minimise) than those arising from an imperfect head-count.

ECONOMIST: Statistics

As students, you should keep in mind that all these numbers are estimates based on samples, which are thus subject to sampling error (as well as other types of errors).

FORBES: The Jobs Report: How It's Made, What It Means