Lynda Finn, President of Statistical Insight, has written an article on how to create a control chart for seasonal or trending data (where there is an underlying structural variation in the data). Essentially you need to account for the structural variation to create the control limits for the control chart. She also provides a Minitab project file. Both are available for download from the Curious Cat Management Improvement Library.
At the recent Annual W. Edwards Deming Institute Annual conference (this year held in Madison, Wisconsin) Peter Scholtes gave an excellent speech on the 6 Leadership Competencies from his book: The Leader’s Handbook. Those competencies are:
- The ability to think in terms of systems, and knowing how to lead systems.
- The ability to understand the variability of work in planning an problem solving
- Understanding how we learn, develop and improve. Leading true learning and improvement.
- Understanding people and why they behave as they do.
- Understanding the interdependence and interaction between systems, variation, learning and human behavior. Knowing how each affects the other.
- Giving visions, meaning, direction and focus to the organization.
As those familiar with Dr. Deming will immediately note those are very closely tied to Deming’s 4 areas of management. I am a friend (and manage Peter’s website so I am biased) but as I have said before anyone interested in management should read his book (the competencies are discussed in chapter 2).
The photo shows George Box, John Hunter and Peter Scholtes (from left to right) at the MAQIN reception the night before the conference. Two previous mayors of Madison introduced Peter’s talk: Paul Soglin and Joe Sensenbrenner.
What’s Making Us Sick Is an Epidemic of Diagnoses by Dr. Welch, Dr. Schwartz and Dr. Woloshin:
This epidemic is a threat to your health. It has two distinct sources. One is the medicalization of everyday life. Most of us experience physical or emotional sensations we don’t like, and in the past, this was considered a part of life. Increasingly, however, such sensations are considered symptoms of disease.
Lack of understanding systems and understanding variation? To me this is a very similar idea to seeing everything as a special cause and addressing each problem with special cause thinking (find the one special cause). Instead, often (97+% according to Dr. Deming) the most effective improvement strategy is to examine the whole system (use common cause thinking). This view in itself, might be a sign that I have “Demingitis” – the propensity to see the excessive focus on special cause thinking everywhere I look.
Every system has variation. Common cause variation is the variation due to the current system. Dr. Deming increased his estimate of variation due to the system (common cause variation) to 97% (earlier in his life he cited figures around 80%). Special cause variation is that due to some special (not part of the system) cause.
The control chart (in addition to other things) helps managers to avoid tampering (taking action on common cause variation as though it were a special cause). In order to take action against the results of common cause variation the performance of the system the system itself must be changed. A systemic improvement approach is needed.
To take action against a special cause, that isolated special cause can be examined. Unfortunately that approach (the one we tend to use almost all the time) is the wrong approach for systemic problems (which Deming estimated at 97% of the problems).
That doesn’t mean it is not possible to improve results by treating all problems as some special event. Examining each failure in isolation is just is not as effective. Instead examine the system that produced those results is the best method. The control chart provides a measurement of the system. The chart will show what the process is capable of producing and how much variation is in the system now.
If you would like to reduce the variation picking the highest data values (within the control limits) and trying to study them to figure out why they are so high is not effective. Instead you should study the whole system and figure out what systemic changes to make. One method to encourage this type of thinking is asking why 5 times. It seeks to find the systemic reasons for individual results.
The Customer Knows Best? Better Think Again by Anthony W. Ulwick
Excellent point. Some management ideas are pretty easy and straight forward. But many management practices require knowledge and judgment to apply them successfully. Easy solutions may be desired, but, often you must choose between easy and effective (hint, I suggest effective is the better target).
Quality Quandaries: Six Sigma, Process Drift, Capability Indices, and Feedback Adjustment by George Box and Alberto Luceno. This article is for the more statistically inclined.
The Six Sigma specification makes an allowance of 1.5 standard deviations for process drift. Simple ways in which a major part of such drift can be removed are given. These employ feedback adjustment methods specifically designed for SPC applications.
Feedback adjustment can be dangerous: tampering. In fact, I would say attempting it is likely to be tampering, unless those doing so are careful and knowledgeable. It might be wise to read Box and Luceno’s book on the topic – Statistical Control: By Monitoring and Feedback Adjustment if you are tempted to try.
The Man Driving Toyota from Business Week:
We should never be satisfied with the current status. In each division, function, or region, we still have numerous problems to cope with. We need to identify each one of those tasks or problems and fully recognize them and pursue the causes. This needs to be done by all the people working for Toyota.
I think, this echoes my recent comment on post, Is Quality Foolproof? (unfortunately the link is broken, so I removed it. Luckily I posted my comments here so they are not gone), on the Vision Thing blog: