Margin of error facts for kids
The margin of error is a way to measure the sampling error in the results of a statistical survey. A bigger margin of error means that the results are less certain. Margins of error occur when a population is incompletely sampled. Usually, the margin of error is defined as the radius (half the width) of a confidence interval for a given sample.
Images for kids

Probability densities of polls of different sizes, each colorcoded to its 95% confidence interval (below), margin of error (left), and sample size (right). Each interval reflects the range within which one may have 95% confidence that the true percentage may be found, given a reported percentage of 50%. The margin of error is half the confidence interval (also, the radius of the interval). The larger the sample, the smaller the margin of error. Also, the further from 50% the reported percentage, the smaller the margin of error.