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Binomial Probablility Calculator Excel File


This excel file will help assess the potential utlity of a case-control study for a foodborne disease outbreak investigation. It calculates cumulative binomial probabilities.

During an investigation of a cluster of salmonellosis cases, four of your eight cases recall eating alfalfa sprouts during the week before onset. Is that a suspiciously high proportion? If you can estimate the "background" rate of sprout consumption in your population (e.g., from survey data or even a wild guess), you can calculate the odds of getting as many or more sprouts eaters in a sample of N independent cases by chance alone. Hint: the background rate of sprout consumption is <10%, and finding even 4/8 by chance alone is highly unlikely.

Primary Toolkit:

Infectious Disease Prevention and Control Toolkit

Secondary Toolkits:

Infectious Disease Prevention and Control Toolkit,Epidemiology Toolkit

Keyword Area:

Environmental Health, Epidemiology, Food Safety


Institutional Author:

Oregon Public Health Division





The NACCHO Toolbox is a repository of available resources to help local public health practitioners. Tools are produced by local, state, and federal agencies, as well as academic institutions and other stakeholders. The contents of this Toolbox are solely the responsibility of the authors and do not necessarily reflect any official recommendations of NACCHO. NACCHO makes no express or implied warranty with respect to the contents and disclaims liability for any damages arising from or connected to the use of the material in this Toolbox.