Assessing the accuracy of polls and surveys.

Direct measurements of public opinion about national affairs appear with increasing frequency in all of the mass media. While such survey results are often with statements as to expected error margins, discrepancies between multiple surveys in the news at the same time on what seem to be the same topics may convince casual consumers that such error margins must be considerably understated. A brief review of the several sources of variability and fixed bias in such surveys provides a clearer frame of reference for the evaluation of such data.