CDC Epidemic Intelligence Service
"The EIS was established in 1951 following the start of the Korean War as an early warning system against biological warfare and man-made epidemics.Over the past 50 years, EIS officers have played pivotal roles in combating the root causes of major epidemics .More recently, EIS officers have documented the obesity epidemic in the United States, helped states reduce tobacco use, and studied whether disease outbreaks were a result of bioterrorism."

The site contains a number of epidemiological studies; more importantly it gives a step-by-step guide on how to interpret the results of the study.