All improvement efforts require a framework. No matter what we’re doing, we all need some way to align our efforts and focus on a specific objective. During my 50 years in this business, I’ve seen people use many different improvement frameworks. Most of these have been variations on either PDSA (plan, do, study, act) or DMAIC (define, measure, analyze, improve, control).
ADVERTISEMENT |
This column will reveal the three fundamental questions that form the basis for all of these frameworks. Answer these three questions and you’ll have a road map for success. The many different improvement approaches simply dress up these three questions with different details. These details often obscure the fact that there’s a simple, proven approach to process improvement.
The ideal
The first question is, “What do you want to accomplish?” Until you have a clearly stated objective, you risk everyone running off in different directions, working on their own pet projects and not cooperating for the common good. Whether it’s a specific project with a limited scope, or the general day-to-day operations of your organization, a clearly stated purpose or objective is important to help focus the thoughts and efforts of everyone involved.
In defining our objective, it’s important to know what our current process is capable of delivering. Asking for more will require a new process. Settling for less is just lazy.
Any situation in which this question remains unanswered will rapidly deteriorate into chaos. However, merely specifying your objective will not be enough.
The methodology
The second question is, “By what method will you accomplish your objective?” While it may be necessary to have a goal, merely having a goal is, by itself, not sufficient. Remember the old saying, “If wishes were horses, then beggars would ride.” Until you have a plan for achieving your objective, it will be nothing more than a dream. Moreover, your plan will need to identify the discrepancies between the goal and the current state of affairs, and it will also need a methodology for moving toward the goal.
The judgment
The third question is, “How will you know when you have accomplished your objective?” If you’re going to have a goal, and if you hope to move toward that goal, then you’ll also need some way to measure how far you’ve come and how far you have yet to go. Of course, the greatest obstacle to knowing when you’ve accomplished your objective is the fact that data always vary. Any measure you might use will go up or down from month to month. If you don’t know how to separate routine variation from a signal that a change has occurred, you won’t know if you’ve made any progress toward your goal.
Historical context for the three questions
Walter Shewhart discussed these three questions in the context of making a product. He referred to them under the headings of:
1. Specifications
2. Production
3. Inspection
W. Edwards Deming talked about these three questions in terms of 1) having a criterion; 2) having a test method for determining compliance to the criterion; and 3) having a decision rule for interpreting the results of the test.
Regardless of the nomenclature, these questions define the essence of how to get things done. Until we can answer the second and third questions, all of our targets, goals, and plans are merely wishes and hopes. To turn dreams into reality, we have to have some specific method for making them come true, and some way to judge when they have come true.
In his second book, Statistical Method from the Viewpoint of Quality Control (Graduate School of the Department of Agriculture, 1939), Shewhart returned to the idea embodied in these three questions and showed how a process behavior chart 1) defines an ideal; 2) provides a methodology; and 3) allows us to make a judgment.
Specifically, in Figure 1 the natural process limits on an X chart define the process potential. They define what a predictable process has produced and what it’s likely to continue to produce. On the other hand, when a process is operated unpredictably, these limits approximate what that process can achieve when operated predictably. To use Shewhart’s words, the natural process limits approximate the ideal of what the process can do when it’s operated up to its full potential. They define what any process can accomplish without resorting to guesswork or arbitrary goals.
In Figure 2, the running record of the individual values defines the actual process performance. Whenever a point goes outside the bounds of the natural process limits, it identifies a departure from the routine, a change in the process, and the presence of an assignable cause of exceptional variation. By identifying these points, the process behavior chart provides us with a methodology for when to look for assignable causes. When we can identify an assignable cause and move it from the set of uncontrolled factors to the set of controlled factors, we’ll be removing a significant source of variation from the product stream. By removing sources of variation from the product stream, we’re not merely maintaining the status quo but rather are tightening up on the process variation and improving both the predictability of the process and the consistency of the process outcomes.
Thus, the process behavior chart gives us a methodology for actually moving our process toward the ideal. Moreover, this methodology doesn’t require you to figure out in advance what the problems are. Nor does it require you to choose what variables to study with experiments. Rather, it simply lets you listen to the voice of the process to learn what really happens in practice.
Finally, in Figure 3, by combining both the process potential and the process performance on the same graph, the process behavior chart allows us to judge how close our process is coming to operating up to its full potential. The absence of points outside the limits tells of a reasonable degree of predictability. For an unpredictable process, the number of points outside the limits and the extent to which they fall outside the limits will quantify the degree of unpredictability.
Summary
The general framework defined by these three questions has been called an operational definition. Operational definitions allow you to get down to business. When you have the answers to the three questions, you have what you need to succeed. Leave one of the three questions unanswered and all you’ll have is the basis for an argument.
As may be seen above, the process behavior chart provides us with an operational definition of how to get the most out of any process. When you use a process behavior chart in this way, it becomes the locomotive for your improvement efforts. You don’t have to work on improving the measurement process first. You don’t have to first do an FMEA to think of everything that might go wrong. You don’t have to brainstorm to find a problem to work on. You simply listen to your production process and let it tell you what to fix and when to fix it. When you successfully fix a problem, the chart will show this success. When you fail to fix a problem, the chart will continue to nag you.
When you use a process behavior chart on a continuing basis, you’ll be repeatedly applying the three questions for success as shown in Figure 4. This will allow you to continually improve your processes, which will reduce costs, increase productivity, and improve your competitive position.
Add new comment