A Quality Monitoring System
Lindsley contends that most of the important changes occurring in any process are seldom visible in the types of percentage graphs that he calls "stretch-to-fill" charts. He cites one study at Florida State University comparing percent correct as a measure of academic performance (of elementary and high school students) with measuring the number of correct/incorrect responses per minute. The study revealed that the correct/incorrect per unit of time measure recognized 40 times more performance changes than did percent correct. "Percent is greatly misinforming. People think when you do percent correct you have an accurate indicator of how many are right or wrong, but it is contaminated by the total," he stated. The Standard Celeration Chart is capable of indicating variables on performance or processes that may occur 100,000 times a day, as is often the case in manufacturing, while at the same time highlighting small, but significant changes - changes that might happen only 10 times per day. The chart is designed not to tell you what to do, but to help you make decisions and pick out salient features of the performance or process in a matter of minutes. Lindsley points out that statisticians have overcomplicated certain quality-control procedures, SPC being one of them, to the point that they no longer serve the purpose for which they were designed. Following are some of his remarks on the use of the Standard Celeration Chart and its role in industry as well as education: "Statisticians insist on unnecessary precision. For example, if I ask you how much money you made last year, you don't say, 'I can't tell you. I haven't worked it out in cents, yet.' If you see a flock of geese flying overhead and three are out of the group, do you need to know whether they are males or females or what they had for dinner last night? No, you simply can see that they are out of the group. All that statistics really tells you is what is out of the group.
Shewhart, a noted statistician and author, didn't know how to handle raw data. He grouped it and tried to randomize it, but found that the order of occurrence has got to be there or you can't monitor quality. SPC shows us the common causes and then the extra 'bounces' in data which are the special causes SPC tries to locate. “With the Standard Celeration Chart we don't have to compute averages. We don't have to compute estimated standard deviation. We don't have to set upper or lower control limits. We do it all with that beautiful thing called the unaided human eye and a semi-logarithmic chart. "That is the power and this is the message: With the human eye and raw data appropriately presented, line personnel can do SPC and the data themselves. They do not need to do statistics on these data to perceive deviations and special causes. The statistician shows an inability to accept how skillful the human observer really is. In quality control we have to get the lemons out of the process fast. Let your workers report on the lemons and the exemplars in a system by teaching them to chart themselves."
Volume 10 Number 3.
©1992 Performance management Magazine.
All Rights Reserved
Founded in 1978, and headquartered in Atlanta, GA, Aubrey Daniels International (ADI) works with such diverse clients as Aflac, Duke Energy, Lafarge, Malt-O-Meal, M&T Bank, Medco, NASA, Roche Labs, Sears, and Tecnatom to systematically accelerate discretionary effort—where people consistently choose to do more than the minimum required. Whether at an individual, departmental or organizational level, ADI provides the tools and methodologies to help move people towards positive, results-driven accomplishments.
Connect With Us
aubreydaniels.com/stay-connected
web: AubreyDaniels.com blog: aubreydanielsblog.com twitter: twitter.com/aubreydaniels
facebook: facebook.com/Aubrey.Daniels.International
