What do polls really tell us?

With the Presidential Primaries in full swing it’s important to review the statistical nature of polls. The media can sometimes overestimate the value of information from these surveys and rely on a tool that is a random measure. First issue, is the sample biased? The underlying assumption that is relied upon to conduct a scientific poll is the random sample. If the sample generated is not random then the results should be examined closely. Second issue, what is the underlying population that is being sampled? The population needs to be clearly defined and should be reported when citing results from a poll. Is the population sampled registered voters, party affiliations, people listed in the phone book? The poll is designed to infer characteristics about the population and if there is confusion about the precise definition then interpretation of the results can be misleading. Third issue, the media often misinterpret the meaning of significance and confidence levels. The final issue here will be addressed in an example in the next post.