Margin of Error
Etymology
“Margin” is from Latin “margo” (edge or border); “error” from Latin “errare” (to wander). Together they name the edge within which the true figure is expected to wander around the estimate.
noun phrase · /MAR-jin uhv ER-er/
The amount by which a survey estimate could plausibly differ from the true value due to sampling.
What it names
It is the fine print that turns a dramatic poll lead into a statistical tie.
Example
A candidate polling at 48 percent versus 45 percent with a margin of error of plus-or-minus 3 points is not really ahead — the race is a dead heat.
Related idea
The margin of error captures only random sampling error, not the bigger dangers — a biased sample or leading questions — so a tiny margin can still sit atop a badly wrong poll; it is the visible half of the confidence interval.