Researchers looked at Wikipedia entries on the 10 most costly medical conditions in the United States (in terms of public and private expenditure), checking them against peer-reviewed medical research.

They found that nine of 10 of them had “statistically significant discordance” with medical literature. The basic conclusion: Wikipedia articles about medical conditions “contain many errors.” (The researchers didn’t judge Wikipedia entries by what they didn’t say, so errors of omission weren’t counted.)