[Air-L] web demographics

I am researching children's use of the Internet and looking for recommendations for websites that offer reliable demographics for web research. Do demographics available at Alexa or Quantcast, for example, offer accurate representations of site visitors? As variables such as age, gender, etc., can be different than that of an actual website user, are all web demographics to be considered unofficial estimates? Thank-you in advance for any suggestions. Lillian C. Spina-Caza PhD Candidate, ABD Language, Literature & Communication Rensselaer Polytechnic Institute 110 8th Street Troy, New York 12180 USA spinal@rpi.edu