the basic issue in sampling is to decide what the target population T actually is. Then you weight the sample so that each person in the target population has an equal chance w and people not in it have weight zero.
So what is the target population we want to study? --the world's population? --the world's educated population? --everyone with internet access --everyone who ever uses Wikipedia --everyone who use it a lot --everyone who has knowledge to contribute in positive fashion? --everyone who has the internet, skills and potential to contribute? --everyone who has the potential to contribute but does not do so?
Richard Jensen rjensen@uic.edu