One quick note: Most polls report margins of error alongside another technical term, “ confidence interval.” In the most rigorous reporting of polls, you might see a sentence near the end that says ...

Hold your breath and make sure you vote, because the result is likely to be a squeaker.

Confidence intervals are calculated using a mathematical formula that encompasses the sample size, the range of responses and the laws of probability.

An election poll's point estimate is stabbing for the right answer, but the margin of error usually includes the true figure. Sometimes even that can be wrong.

And since pollsters generally use a confidence interval of 95 percent, one out of 20 polls will be a statistical outlier – that is, outside the margin of error – just by chance.