Mark Liberman has an excellent post examining the general public’s understanding of basic statistical concepts such as means, variances, and distributions. Here’s a taste:
Until about a hundred years ago, our language and culture lacked the words and ideas needed to deal with the evaluation and comparison of sampled properties of groups. Even today, only a minuscule proportion of the U.S. population understands even the simplest form of these concepts and terms. Out of the roughly 300 million Americans, I doubt that as many as 500 thousand grasp these ideas to any practical extent, and 50,000 might be a better estimate. The rest of the population is surprisingly uninterested in learning, and even actively resists the intermittent attempts to teach them, despite the fact that in their frequent dealings with social and biomedical scientists they have a practical need to evaluate and compare the numerical properties of representative samples.
Liberman points out that the relevant concepts are fairly recent. The inability (or unwillingness) of the average Joe to “get it” manifests itself in the coverage of science in the popular press. For example, rather than adequately describing the relative risk of some factor on having some disease, syndrome, or other phenotype, most journalists simply tell you that some group of people are more likely to have the phenotype.