Is this likely to be an overestimate or an underestimate of the number of respondents? And maybe there is no bias here. But our choices, and no bias is not one of the choices, so you can imagine, it's going to be one of these three. So I encourage you to pause this video and think about what we just said. We're a senator, we're trying to figure out what percentage of our constituents are very concerned about internet privacy. And we go to the phone book, we sample 100 people, we keep calling them until they answer, and we get that 42% are very concerned. So what's the source of bias?