Geotagging 100M Twitter accounts, independent of location-sharing preferences [pdf]

Key quote: However, there do exist several users who have amassed friends dispersed around the globe. For these users, our approach should not be used to infer location.

So yeah.

Previous post and discussion: https://news.ycombinator.com/item?id=9155890

Impressive work.

Some of the assumptions (people tend to @mention users geographically close to them) don't always hold true, especially in tech, VC, startups, etc.