Epidemiology
The branch of medicine that studies how often diseases occur in different groups of people and why. Epidemiologists are the disease detectives who investigate outbreaks and clusters.
Related terms
Public Health The science and practice of protecting and improving the health of whole communities through education, policy, disease surveillance, and environmental regulation. Observed vs. Expected Rates An epidemiological method of comparing the actual (observed) number of disease cases in a community against the number that would be expected based on state or national averages. A statistically significant gap suggests an environmental cause. Statistically Significant A finding mathematically unlikely to be the result of random chance or coincidence. Used to confirm that a pattern—like a disease cluster—is real and not just noise in the data. Cancer Cluster A greater-than-expected number of cancer cases occurring within a specific group of people in a defined geographic area over a certain period. The CDC's official designation requires intense, long-term statistical analysis.