Understanding Variation—26 Years Later

Abstract:A Quality Progress article published in 1990 stressed the importance of understanding variation when interpreting data and the high costs of failure to appreciate and account for both common and special variations. Since that time, data sources have multiplied and data sets have grown vastly larger and richer, enabling greater understanding of the stable and unstable processes that contribute to variation and offering more informed insights for potential systematic improvement. The authors use Shewhart's theory and methods to analyze publicly available data regarding falls with injury, work fatalities, and high school drop-out rates. Key questions asked in each case are whether the process is stable or unstable and what action makes sense in view of the stability or instability of …

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Very well written. Very useful. Congrats to the authors and all ASQ Quality Progress contributors.
--Jose Dorbecker, 06-02-2017


good informative article.
pareto charts might be also more suitable; because data set is not collected consequently.

Aylin N. M.
ASQ CQPA, CQE, CQA
--Aylin N. M., 01-18-2017


using control charts are very useful to
define / identify specific / assignable / random causes of variation

Aylin N. M.
--Aylin Nafia MInikus, 01-03-2017


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