Searching and researching information to purchase a car or an iPad isn't the same as conducting a search for breast or prostate cancer on Google, Bing, Yahoo, or Ask. Marketers know that based on ranking and other factors, results can vary. But for consumers searching for information on life-theatening diseases, the differing query results for the same keywords can become confusing. Researchers from the University of Missouri compared four major Internet search engines for obtaining medical and health information, and found that each has its own method for deciding the sites to serve up and how to rank them. The study defines usefulness for the four engines, categorizes health-related Web sites, and makes suggestions on who should search on what engine for the best results.