Two Canadian researchers examined 47 systems used to rate Web sites providing health information on the Internet and found that 14 of these described their rating criteria, only 5 provided instructions for their use, and none provided information on whether they had been validated. The researchers concluded:
Many incompletely developed instruments to evaluate health information exist on the Internet. It is unclear, however, whether they should exist in the first place, whether they measure what they claim to measure, or whether they lead to more good than harm.
Jadad AR, Gagliardi A. Rating Health Information on the Internet. JAMA 279:611-614, 1998.