Polls (statistics)

As we head towards another election year, we are already starting to see advertisements and hear debates from the candidates. An important tool in campaigning is also the polls. Most polls are qualified with a stated margin of error. What does this mean? Can we trust the polls? According to Scientific American, “The margin of error depends inversely on the square root of the sample size.” The bigger the sample size, the smaller the margin of error. However, even this calculation can’t correct all errors. Polls can be biased. For example, a phone poll doesn’t reach the segment of the population without phones. Perhaps even more importantly, people change their minds.