Understanding and Controlling Variation in Public HealthMason, Marlene J. MBA, BSN; Moran, John W. MBA, MS, PhD, CMC, CQIA, CMQ/OEJournal of Public Health Management & Practice: January/February 2012 - Volume 18 - Issue 1 - p 74–78 doi: 10.1097/PHH.0b013e318233d5eb Commentary Abstract In Brief Author Information Variation in work processes is a critically important concept and method for creating true and sustainable improvement in public health services and activities. This article describes the concept of variation based on W. Edwards Deming's profound knowledge and defines basic terms such as common cause and special cause variation. Control charts are explained as the primary tool for calculating variation within work processes. The article also provides an example of how variation theory can be applied to create sustainable improvement in public health. Variation is the difference between what should be happening (ideal) and what is happening (current state). This commentary focuses on understanding and controlling variation in public health practice. MarMason Consulting LLC, Kirkland, Washington (Ms Mason); and Public Health Foundation, and University of Minnesota School of Public Health, Minneapolis (Dr Moran). Correspondence: Marlene (Marni) Mason, MBA, BSN, 10620NE 125th Place, Kirkland, WA 98034 (email@example.com). Disclosure: The authors declare no conflict of interest. © 2012 Lippincott Williams & Wilkins, Inc.