How are services like Alexa and Google Analytics capable of tracking visitors' age, gender, college education, and so forth?
A:
I did some research, and apparently these demographics are tracked the same way TV audience demographics are tracked. There are people who browse with their (Alexa's) toolbars, which keeps track of the sites visited. These people willingly (?) supply information like age, gender, etc. and Alexa extrapolates the general demographics from this sample. This of course leaves room for bias, but that's a problem with statistics.
pessimopoppotamus
2010-08-25 19:10:30