Margin of error

The margin of error is a statistic expressing the amount of random sampling error in a survey's results. The larger the margin of error, the less confidence one should have that the poll's reported results are close to the 'true' figures; that is, the figures for the whole population. The margin of error is positive whenever a population is incompletely sampled and the outcome measure has positive variance (that is, it varies). The margin of error is a statistic expressing the amount of random sampling error in a survey's results. The larger the margin of error, the less confidence one should have that the poll's reported results are close to the 'true' figures; that is, the figures for the whole population. The margin of error is positive whenever a population is incompletely sampled and the outcome measure has positive variance (that is, it varies). The term 'margin of error' is often used in non-survey contexts to indicate observational error in reporting measured quantities. Margin of error is usually defined as the 'radius' (or half the width) of a confidence interval for a particular statistic from a survey. One example is the percent of people who prefer product A versus product B. When a single, global margin of error is reported for a survey, it refers to the maximum margin of error for all reported percentages using the full sample from the survey. If the statistic is a percentage, this maximum margin of error can be calculated as the radius of the confidence interval for a reported percentage of 50%.