1. Johnson N, Xu C, Zhao Z, et al. Human group formation in online guilds and offline gangs driven by a common team dynamic. Physical Review E. 2009;79(6):1-11. Available at: http://link.aps.org/doi/10.1103/PhysRevE.79.066117.
This paper looks at building a simple model of how people decide to join or move between guilds or gangs, using membership data from World of Warcraft guilds and LA street gangs.
They attempt two types of model: where people choose to join groups where all members have the same attributes as them ('kinship') and where people choose to join groups where they complement the existing membership ('team formation'). The model that fitted the data most closely was the team formation model. I think that's extremely interesting, as I'm suggesting that guilds do form from players with similar playing styles, so perhaps this is a different angle. (By playing style I think I'm meaning subtle differences in emphasis, i.e. more emphasis on exploration vs raiding vs PvP etc.)
In addition to looking at both sets of data as a whole, they then divide the groups by 'ethnicity'. This is obvious in terms of the gangs, but for the WoW data they split it by server. This turns out to be a good fit because as it is not possible to change your ethnicity in real life, it is also difficult/expensive to move your character between servers in WoW. They find that although the model fits all the variations of ethnicity they need to tweak some of the constants slightly, suggesting that there are very subtle differences in behaviour not only between different gang ethnicities in LA (which might be expected - different backgrounds and cultural values) but also in between servers in WoW (same game, so what causes that?!).
Good analogy to job finding, and actually rather tallies with my empirical experience that teams tend to take on the character of their head (who does the hiring) while looking for members that complement the group skillset. Again, a difference between the two definitions of what people look for in a team - similar values, different skills.