While it is useful to know the size of the population of the three MUDs, this is difficult to ascertain. It is only possible to get the number of players. Altogether, there were about five hundred and fifty active players in the three MUDs at the time of the study. But many players have more than one character in one MUD, and many of them play more than one MUD.  In this study, 25% of the players reported playing only one character in only one MUD. Another 25% played more than one character in one MUD, the other half reported playing one character in several MUDs or several characters in several MUDs. In a more recent study (Utz, 1999) even more players reported having more than one character. So, the number of active players should be seen as limiting value, the actual number of MUDders is at best half. However, the sample covers quite a lot of the population of the three MUDs.