Learn about a new way to use Fishbone diagrams to identify the relationships between sources of waste and undesired effects.
Ishikawa (Fishbone) diagrams typically are used by teams to brainstorm and organize potential causes for an undesired effect. But last week, I learned about a new way to use this quality tool from management consultant Bill Peterson, who also teaches at the University of Tennessee. Bill has been using Ishikawa diagrams to identify the relationships between sources of waste and undesired effects, which can help you identify the causes with the highest impact.
Bill’s technique is straightforward: instead of labeling each of the main bones with the 6M’s (Manpower, Materials, Machines, Methods, Measurements and Mother Nature/Environment) just replace them with types of waste. By making this shift and removing “Man” as one of the cause categories, he also eliminated one of the pitfalls of root cause analysis using the fishbone diagram: finger-pointing and placing blame.
“What’s the central thesis of lean? The identification and elimination of wastes. In lean, those wastes are always the root cause of bad process outcomes. So why not organize a brainstorm around the 8 Wastes that plague the business office?” -- Bill Peterson
In the figure below, Bill uses the TIMWOODS categories, replacing the S (Skills) category with Lack of Organizational Focus. Through his consulting practice, he found that a company’s lack of focus and alignment has far greater impact on undesired outcomes than skills or training.
Once the causes are identified, you can apply countermeasures from the lean toolkit like 5S, visual management or standard work to reduce the source of the waste. This technique also provides an easy way to see whether one or more of the waste categories are dominant. For example, if the “waiting” bone is full of potential causes but the “defects” bone is not, look for process bottlenecks to resolve.
Paradies, M. (2018, Nov 6). What Makes a Great Root Cause System? Intelex Community. Available from https://community.intelex.com/explore/posts/what-makes-great-root-cause-system
Peterson, B. (2018, July 17). A Better Way to Brainstorm Root Causes. LeanBP Blog. Available from https://www.leanbp.com/blog/a-better-way-to-brainstorm-root-causes/