A distribution represented as a bell shape,symmetrical on both sides of the peak, which is simultaneously themean, median, and mode, and with both tails extending to infinity
Richard C. Dicker, (Lead Author), Fatima Coronado, Denise Koo and Roy Gibson Parrish, Principles of Epidemiology in Public Health Practice (Glossary of Epidemiology Terms), 3rd Ed., Developed by: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention(CDC), Office of Workforce and Career Development, Career Development Division, Career Paths to Public Health Program, Scientific Education and Professional Development Program Office, GA, The Public Health Foundation, EXCITE!: Excellence in Curriculum Innovation through Teaching Epidemiology and the Science of Public Health, http://www.cdc.gov/excite/library/glossary.htm, USA 2006. (Epid - Amer) {686}