However, it is easier to get an indication of global reach and it indicates an active interest in a club rather than the passive awareness of one.
On July 10 this year @manutd was launched as the verified Manchester United twitter account and the fund for the day was to watch the number of followers grow with each refresh. It is now at about 600,000 followers.
Reinforcing the idea in another Stefan Szymanski book - National Pastimes: How Americans play baseball and the rest of the world plays soccer - it is clear from the social media list just how the global reach for football outstrips that for large US sports franchises. Barcelona have more social media fans than the 30 most valuable major league baseball teams combined.
This will prove to be an important source of data on clubs' off-field performance, especially as the data gets mined for interactions (such as Facebook likes and retweets on Twitter).