How confident can the surveyor be about an estimated margin of error? To measure this, surveys also have what is called a “confidence level”, which is the likelihood that the estimate between seventy and eighty percent in this case is really accurate. Most surveys have a ninety five percent confidence level. In other words, there’s a five percent chance — or a one in twenty possibility — that the overall public opinion doesn’t even fall within the estimated margin of error. Confidence levels and margins of error are based on the size of the sample in comparison to the size of the whole population. They don’t take into account the possibility of inaccuracies in the survey itself. So, next time you survey results, look for the margin of error. And remember there’s still at least a one-in-twenty chance that the real public opinion doesn’t even lie within that margin of error.