How effective we are at solving problems and keeping them solved depends on our ability to address them at their source. When we put out fires but fail to put in measures to prevent similar fires in the future, we fight the same fires again and again. Instead of increasing our fire-fighting budget, we should increase our investment in prevention at the source.
There are a several common techniques for identifying likely root causes. Either for the sake of simplicity, or because it worked in the past, many organizations zero in only one technique. Often this becomes an exercise in compliance, filling out a template rather than thinking through how to approach the problem. No single tool is versatile or reliable enough to get us to root cause in a majority of situations. Different situations call for different tools. When in doubt, we can go a long way with a combination of fish, trees, and go see.
Solving real problems is easiest when we have a firm grip on reality. Reality tends to exist outside of our heads. But we need our heads in order to process objective reality that we can perceive into actionable thought. In short, we need to go see. Finding the prime suspects that cause a problem by observing the process is the simplest and most direct way, but this option is not always available due to the nature of the process or problem. This requires us to use a number of techniques to visualize our thinking.
One common technique is brainstorming. A group of people knowledgeable about the problem get together and list what they think are the causes. On the positive side, this is easy to do. It is just talking. Done in a structured way with affinity diagrams to simplify and organize brainstorming and PICK charts to help to prioritize, brainstorming can support rapid idea generation. Nevertheless, there is the risk that when we brainstorm causes, our thinking can be subjective, unscientific, or not grounded in a thorough understanding of the factors affecting the process. Also, without data to weigh one idea versus the next, the most vocal or highest ranked voices can sway the outcome.
The fishbone diagram is not a form of brainstorming. We should not be generating creative ideas about what could be causing the problem, i.e. guessing. The fishbone diagram works with a predetermined set of factors known to affect the outcome of a process. In general these are known as the “5M” for manpower, material, method, machinery and measurement. These are the factors that contribute to the majority of problems in manufacturing, healthcare, construction, landscaping and so forth. For retail businesses or the sales process of an organization, we can use “5P” for price, promotion, place, people, product.
To identify factors affecting problems in knowledge work, it is a simple matter of adjusting these categories to suit. Simply select four to six plausible factors are known or agreed to affect the outcome the process. An organization that has a limited idea of what factors contribute to a good outcome for their process needs to spend time understanding their process before diving into problem solving.
The fishbone diagram is not a template for 5 why analysis. Although it is possible to show 2, 3, 4 or more links in the cause-and-effect chain, getting to root cause is not its purpose. The fishbone diagram is more of a map of possible sources of variation in the process for further investigation.
A tree diagram looks like a fishbone diagram rotated 45 degrees. However, it serves a very different function. Unlike a fishbone diagram whose purpose is to broaden the list of suspects, the tree diagram is used to narrow down and eliminate possible causes, ideally to one or more addressable root causes. The tree diagram is an appropriate structure for practicing 5 why analysis.
Used in proper combination, these tools and methods help us to see reality clearly, structure our ideas logically and guide our investigation toward finding the root cause.