Huffman based his research on geotagged tweets between March and April of 2010. That means a smallish sample size, sure, but you can't really argue with the black hole of cussin that swallows up Salt Lake City. But what four-letter words were counted, and how? According to Huffman:
I made use of six main swears that came to mind: fuck, shit, bitch, hell, damn, ass
I was running these through Excel (since I had the Tweet data in a spreadsheet), and I had it simply search for those text strings within the message. In most cases, that meant it was a search along the lines of *fuck*, meaning it would catch "fucker," "fuckwit," and other words probably bandied about the UW Cartography Lab in its saltier days. For arse and hell, I kept wildcards out of those words, since there was a chance of catching something like "assume" or "shell" if I did not.