Glossary term
Margin of Error
The plus-or-minus range attached to a poll or estimate, showing how far off it could plausibly be from sampling alone.
Visual intuition
12
8 plausible
estimate
16 plausible
The interval is the plausible zone around an estimate
The margin of error turns a single poll number into a plausible zone on either side of the estimate.
Formula
MOE ≈ 1 / sqrt(n) (rough 95% rule for polls)
Example
A poll of 1,000 voters has a margin of error near ±3 points, so a reported 47% really means 'plausibly between 44% and 50%'.
How It Works
A poll of 1,000 people cannot nail 50 million voters exactly, so it reports 47% ±3: the answer plus a plausible zone for the true share. The margin shrinks slowly — you must quadruple the sample to halve it — and it only covers random , not problems like people refusing to answer or answering untruthfully. When two candidates sit within one margin of each other, the poll genuinely cannot say who leads.
Concepts
Margin of Error
A margin of error is the plus-or-minus range around a survey estimate caused by sampling uncertainty. If two estimates have overlapping uncertainty ranges, the apparent leader may not be truly ahead.
Confidence Intervals
A confidence interval is a range produced by a method that captures the true value a stated share of the time across repeated samples. It describes uncertainty in the estimating method, not a personal guarantee that one already-computed interval contains the truth.
