[dccoolgai]

Interesting article, especially when you think about public polling (political or otherwise). Polling data is going to be heavily biased with people who are willing and have the time to be polled, which may be vastly different than the audience you are trying to model. Seems like the author is talking specifically about something a little more quantitative, but to the general point about these kinds of samples being biased in ways that aren't obvious at first, it has something in common.