误差范围表达了统计结果中的随机波动的大小。这可以视为同样的问卷调查进行多次，其报告的百分比的变化的衡量。误差范围越大，该调查得到的百分比接近“真实”值（也就是在整个样本空间中的百分比）的可能性越低。

误差范围可以通过一次抽样调查得到的每个数字进行计算，除非所进行的是一次非概率抽样。对于以百分比表达的结果，经常可以计算一个最大误差范围，它适用于该调查的所有结果（至少所有基于整个采样的结果）。有时最大误差范围可以直接从采样的大小（回答问卷者的数量）计算。

误差范围通常在三个可信度上给出；99%，95%和90%。99%这个级别是最保守的，而90%的级别是最不保守的。95%的级别最为常用。如果可信度为95％，则整个样本空间的“真实”百分比有95％的可能处于一个问卷的结果的误差范围内。等价的说，误差范围就是95％可信区间的半径。

The margin of error is a statistic expressing the amount of random sampling error in a survey's results. It asserts a likelihood (not a certainty) that the result from a sample is close to the number one would get if the whole population had been queried. The likelihood of a result being "within the margin of error" is itself a probability, commonly 95%, though other values are sometimes used. 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. Margin of error applies whenever a population is incompletely sampled.