SOE has partnered with a team of academic researchers at a number of institutions to help with the group's study of human interactions in the game environment. In order to help, "SOE shared over 60TB of server logs from EverQuest II and additional data collected from a voluntary player survey." Ars Technica has an interesting article about how the data was used, and I personally thought the section on the average player was worth noting:

The average age of players turned out to be 31. ... The older players tended to play more than the kids and, although the total hours played seem large, Dmitri Williams said the time mostly displaced either TV watching or movie going. And the surveys showed those who viewed TV news in the first place continued to do so, suggesting gamers really slotted EQ2 into their entertainment time. Mostly, the gamers seemed healthy; their body mass index was better than the US average and, although they were slightly more depressed than average, they were also less anxious.

You can read the full article, which contains a ton of information, here.