The average American knows about 600 people. How do we know this? Researchers led by my Columbia colleague Tian Zheng posed a series of questions to a representative sample of 1,500 Americans: How many people do you know named Kevin? How many named Karen? How many named Shawn or Sean, Brenda, Keith or Rachel?

After adjusting for various factors (for example, the names are not evenly distributed in age across the population), we determined that participants knew an average of 8.4 people with those names. Social Security records suggest that 1.4 percent of the population has one of the names, and 8.4 divided by 1.4 percent is 600 people.

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Using this clever method of estimating social networks can be tricky. Indeed, the method’s inventors, H. Russell Bernard and Peter Killworth, estimated from an earlier survey that the average American knew only 290 people.