Variation

The Lady Tasting Tea: How Statistics Revolutionized Science in the Twentieth Century

Salsburg begins this book about the modern history of statistics with a scene at tea party in Cambridge England. A lady states that she can tell the difference in tea that has been poured into a cup with milk vs tea that has milk added. Several learned guests at the party immediately challenge the lady. One guest then designs and carries out an experiment to see if the lady’s hypothesis is correct. The name of this guest leading the experiments is Sir Ronald A. Fisher. You will have to read the first chapter to find out if the Lady could tell the difference in methods to add milk to tea. Salsburg does a great job in bringing to life the stories behind the great advancements in statistical methods. The book is geared to the reader who does not have a strong math background. The author does a great job in developing the history with very interesting portraits for the men and women who integrated statistical methods into the scientific questions of the day

Full House: The Spread of Excellence from Plato to Darwin

A Harvard professor of zoology and geology writes this book on variation. Gould's studies of evolution and the nature of progress led him to understand trends as changes in variation rather than just drifts in averages. The analogy of a "full house," the theme of the book, refers to the need to focus on variation of the entire system and not always upon abstract measures of average or central tendency. Gould uses examples such as a drunkard's walk along a sidewalk, the disappearance of .400 hitters in baseball, the evolution of the horse, and the dominance of bacteria as the primary life form on earth. The concept of a "wall" that variation cannot be less than or greater than is an important part of the presentation. For example, life forms can get much larger than bacteria, but it is impossible (the wall) to get smaller. The conclusion that "variation is the ultimate reality of excellence" is a paradigm shift for the study of nature.

A Mathematician Reads the Newspaper

In this book Paulos discusses how we should understand the use and abuse of statistics in news stories. His real life examples on the use of statistics and how they can be used to mislead, is for anyone interested in gaining a more accurate view of the news and the world in which we live. Paulos is very entertaining and closes this book with some excellent advice on what questions should be asked when reading a news story or
reacting to figures.

"Controlling Variation in Health Care: A Consultation from Walter Shewhart" Donald M. Berwick, Medical Care, Vol. 29, No 12, December 1991.

This paper looks at variation from the point of view of health care. Dr. Berwick interprets Shewhart's theories for health care applications. The paper effectively uses examples from the care and treatment of patients to illustrate the importance of Shewhart's theories. The first reaction of physicians to the concept of reducing variation is often negative. Berwick differentiates "intended" and unintended" variation, and emphasizes improvements that can occur by focusing on the unintended variation in health care processes. The paper includes an excellent example of how data is typically generated and used in a hospital setting.

"Understanding Variation," Thomas Nolan and Lloyd Provost, Quality Progress, , ASQC, Milwaukee, May, 1990, pp. 70-78

This paper explains why variation is important to managers and leaders of organizations. The U.S. trade deficit is used to illustrate the general applicability of control charts to management situations. Other case studies include applications in inventory, sales, and project management. The implications of variation to a quality improvement effort are summarized.

"Variation Through the Ages," Lloyd Provost and Cliff Norman, Quality Progress, Special Variation Issue, ASQC, Milwaukee, December, pp. 39-44, 1990

This paper tracks how variation has been viewed from ancient times to the age of the craftsman, the industrial revolution and on through today. Shewhart's contributions to understanding variation are put in historical context. Some ideas on variation in the 21st century are also presented. Note: there are eight other papers dealing with different aspects of variation in this issue.

Uncertainty: A Guide to Dealing with Uncertainty in Quantitative Risk and Policy Analysis

This book discusses the implications of uncertainty (variation in outcomes) on decision making and policy analysis. It is useful as a text for students of variation and as a reference book. Only recently have policy makers begun to understand the important role that uncertainty plays in decisions. Because the uncertainties are often large, it is even more important to understand variation in policy analysis than in the physical sciences. The authors discuss how to incorporate expert judgement in uncertainty analysis and also provide advanced methods using computer models.

Out of the Crisis

Chapter 11
This 62-page chapter presents what is probably the best discussion of variation in writing. The name of the chapter is "Common Causes and Special Causes." The chapter starts with "the central problem in management and in leadership is failure to understand the information in variation." The role
of statistical theory is described, special and common causes defined, the concept of minimizing the economic loss from the mistakes of over reacting and under reacting, the need for rules, and the concept of statistical control is defined. Numerous examples of applications are given. The funnel experiment and the four funnel rules are presented, as well as the red bead exercise.

Economic Control of Quality of Manufactured Product/50th Anniversary Commemorative Issue

This is the definitive work for students of statistical quality control methods. This landmark work touches quality control in all aspects: specifications, problems with inspection of incoming materials and with inspection all along the line, improvement of the process, operational definitions, and problems in the definition of quality. According to Shewhart, the consumer is the most important part of the production-line since, without the consumer, production ceases. Shewhart's book is organized into seven parts:

Part I - Introduction,
Part II - Ways of Expressing Quality of Product,
Part III - Basis for Specification of Quality Control,
Part IV - Sampling Fluctuations in Quality,
Part V - Statistical Basis for Specification of Standard Quality,
Part VI - Allowable Variability in Quality, and
Part VII - Quality Control in Practice.

To Shewhart, quality control means every activity and every technique that can contribute to materially better living through economy in manufacture, and how the product behaves in use. This book is as useful in accomplishing this purpose today as it was when printed in 1931.