Annoying article in the New York Times recently, one that held much promise: "Up Close on Baseball’s Borders." The authors use Facebook data to determine the boundaries of US baseball (MLB) team fan geography. Except this doesn't work, because Facebook is not everyone. Is Facebook statistically representative on this measure? We don't know. Is this only those who "like" a team, have their location entered, and have their accounts public? It appears so. That's a pretty specific group, even if it is numerically large.
Millions of [Facebook users] do make their preferences public on Facebook...And, from our knowledge of Facebook and common sense, that means that millions don't.
We were able to create an unprecedented look at the geography of baseball fandom...Well, no, not at all of baseball fandom, it is a look at:
- Facebook users....
- Who also make their profiles public....
- Who also "like" an MLB team.
One group of die-hard baseball fans this data does not contain, I guarantee you, is children who are baseball fans, since children are not (usually) on Facebook. Young kids can be so into their teams ("their" teams, note!). Kids' affiliations will be influenced by their geography, their friends, and their parents, although my nephew likes Kevin Durant but my nephew lives in NYC and has never been to Oklahoma, so it is not always straightforward.
Dear New York Times people who wrote this article -- you have oversold your data! You can do better!