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Our Favorite QI Tools
Concentration Diagrams
November 2006 - Vol 3, Issue 3
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Greetings!

Greetings from Vermont! It is stick season here; the time in between foliage season and ski season. I have come to really appreciate the beauty of the bare, leafless trees that grace our countryside. Each type of tree has a distinct pattern; some perfectly round, others oblong, and some are just wild looking, but the pattern tells you what kind of tree it is. Patterns are helpful in solving quality-related problems too and one of the best tools for displaying a pattern is the concentration diagram.

Concentration diagrams are the embodiment of the old adage: "A picture is worth a thousand words." A concentration diagram is a visual data display tool that literally shows where defects or problems are concentrated. Seeing the pattern of defects can often be the catalyst to get to the root cause(s) of a problem and ensure the problem is solved for good.

Since concentration diagrams literally paint a picture of the problem, they are one of the most powerful data collection/display/analysis tools we have. Unfortunately, they are one of the most underutilized tools as well.


Ray Mikulak is president of Resource Engineering, Inc. You can contact him at 800-810-8326 or 802- 496-5888 or by e-mail at raym@reseng.com.
Concentration diagrams are incredibly easy to use; data collection and data analysis are both a snap and are done in just one step, not two separate steps. There is no need to develop forms to collect data; depending on the scope of the study, a print of the part, a map of the area or a copy of a procedural form can be used to collect the data.

The dots or "x's" used to plot incidents or instances of the problem or defect create a visual display that usually provides clues to potential causes of the problem. Using the picture of the data (the concentration diagram), ask the following questions about what you are seeing:

  • Is there a pattern here and what could it be telling us?
  • Why are the defects concentrated in a particular area or areas?
  • Why are there NOT defects in some areas? (Sometimes this question is as important as why there are problems in other areas.)
  • What could be causing the pattern?
Developing "theories" to help answer these questions should put you on the path to finding the root cause(s).

Robin McDermott is director of training for Resource Engineering, Inc. You can contact her at 800-810- 8326 or 802-496-5888 or by e-mail at robinm@reseng.com.

  1. Add more visual clues by color-coding the data plotted. For example, use red dots or "x's" for 1st shift, green for 2nd shift, blue for 3rd shift to further segment the data and highlight concentrations by sub-category.
  2. Combine two data collection tools at the same time. For example, combine a workflow diagram and a concentration diagram to show each "stop" a part makes in a production process.
  3. Use transparency film to collect data for specific periods of time, and then stack the transparencies on top of each other to search for similarities (or differences) in the concentration of defects.

Our 8-D computer-based training program provides comprehensive training in the 8- Discipline problem-solving process. With 8-D Problem-Solving you will not only learn a systematic way to tackle problems but you will have access to tutorials on 48 problem-solving tools as well.

8-D Problem-Solving has two units: Getting Started and the 8-Discipline Process. The Getting Started unit focuses on the importance of data in any problem- solving process and the role of teams versus individuals (working alone) in solving problems. In Unit 2, the 8-Discipline Process, there are eight lessons, one for each discipline.

At the end of each unit, learners take the "Challenge" to test their comprehension of the body of knowledge covered in the unit. Want to try out a free lesson on 8-D Problem-Solving? Click here.


Carolyn Burke is Sr. Customer Service Representative. She can be reached toll free directly at 866-791-1003 or by e-mail at carolynb@reseng.com.

We hope that this issue of our newsletter has gotten you thinking about how you might be able to use concentration diagrams in your job and on problem- solving teams. Concentration diagrams are a great way to collect and display data. With a little creativity you may find that they become your favorite and most helpful QI tool.

Sincerely,
Robin McDermott
Resource Engineering, Inc.

phone: 802-496-5888 or 800-810-8326