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Data & Analytics · Foundational

Margin of Error (MOE)

Half the width of a confidence interval: the critical value multiplied by the standard error.

Definition

To halve the margin of error you need roughly four times the sample size. Polls often report ±3 points at 95% confidence, which takes about 1,000 respondents.

Exam tip

Margin of error falls with the square root of n, not linearly.

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