An anonymous reader writes with news about a study that investigated the effectiveness of Yelp reviews in pinpointing the source of foodborne illnesses. "In 2012, New York City's Department of Health and Mental Hygiene (DOHMH) found that residents weren't turning to the city's free 311 service to make such complaints, but rather they were reporting their experiences in Yelp reviews. So the CDC, in collaboration with the New York City DOHMH, Yelp, and Columbia University, conducted a nine-month long research into the effectiveness of using online reviews to identify sources of foodborne illnesses. The study discovered 468 actionable complaints, 97% of which hadn't been officially reported to the city, and analyzed roughly 294,000 Yelp restaurant reviews. Subsequent investigations on suspected restaurants turned up evidence of bare-handed food handling, cross-contamination, or even the presence of mice and cockroaches. The study concluded that providing the public with more options for reporting complaints about restaurants, particularly in the social media sphere, would help in the identification and possible closure of sources of foodborne illnesses."