New Uses For Old Tools Part II: Causal Tools

Jeff Cole

Last month we went tactical and looked at how FMEA could be applied to your process change efforts. Keeping on that same path, this month we’ll explore how to use several causal tools from your Six Sigma tool box to help make your process change efforts successful.

Root Cause Analysis (RCA) tools include simple techniques such as 5-Whys, Cause and Effect Diagrams, Causal Trees and Affinity Diagrams/KJ Analysis. There are also techniques requiring some data like Multi-Vari analysis and Pareto Charts, plus statistical classics such as t-tests, ANOVA, Chi-Square, Correlation, etc. For now, we’ll look at a couple of the simpler Root Cause Analysis tools that don’t require software or any data collection.

Why Aren’t People Following the New Process?

One of the more profound issues we struggle with involves understanding why people do not engage in the new process you have just designed or improved. A common theme running through all of the Street Smarts articles is that if you don’t follow the new process, you’ve wasted your time and money. The classic use of tools like Cause and Effect diagrams and 5-Whys in DMAIC is to uncover the root cause of why a process was broken to begin with. Many limit the use of those Root Cause Analysis tools to the Analyze step. However, once you have improved the process and are running a pilot or full-scale rollout, you must govern the process and ensure people are engaging in it properly. Our alternate use of the Root Cause Analysis tools involves a new perspective: "Why aren’t people following the new process?" This analysis can be done proactively prior to the rollout in order to anticipate problems and bullet-proof it. It can also be done at any point in the rollout when you encounter a lack of engagement.

How it Works

Let’s focus on the simplest Root Cause Analysis tools: Causal Trees and the technique of 5-Whys. This is much like a small child, asking "Why?" over and over, and is actually a valid technique! It helps drill down past symptoms to the true root cause of a problem. There’s no magic in the number five—you may hit a terminal point after four whys, eight whys, etc. Just keep drilling down to the root cause. A Causal Tree is a graphical way of depicting the 5-Whys and is sometimes preferred by those who don’t like the more free-form way a Cause and Effect diagram looks.


Start by placing the problem in a box on the left side of the page—in our case, "People are not following the new process." Street Smart Tip: if someone is not engaging it’s because of either ability or willingness issues (or both). So we can’t go wrong by starting our Causal Tree off with those two items. We then flesh out the ability path—they want to follow the process but can’t—maybe due to lack of knowledge, tools, permissions, etc. Then onto the next level—"Why don’t they have the tools, permission, etc.?" and so on until we reach a terminal point where we can’t logically drill further or it doesn’t make sense to keep drilling down.

Now it’s off to the willingness path—they can follow the process but chose not to—possibly due to perceived lack of value, preferred the old process, no consequences for not following, manager said they didn’t have to, other priorities, etc. Like above, keep fleshing out the levels. By the way—the ability path is often much simpler to correct than the willingness path. If constructed properly, the Causal Tree can be read cleanly forwards (asking "Why?") or backwards (answering "May lead to"). (Click on diagram to enlarge)

You can use the Cause and Effect Diagram (also known as an Ishikawa Diagram or Fishbone Diagram) in a similar fashion. Place your problem in the "head of the fish" on the right side of the page, draw a main spine or arrow into it and then brainstorm and attach causes and sub-causes. You can use either an affinity-based approach or the classic 5Ms and 1 P categories (Machines, Materials, Methods, Measurements, Mother Nature and People). Under the people category you can again start with Ability and Willingness as sub-causes.

Lastly, you could create an affinity diagram. Give each person on the team a pad of post-its and ask them to write down as many reasons as they can (one per post-it) as to why people aren’t following the new process. Slap the notes haphazardly on the wall and start grouping similar items (those that have an "affinity" to each other). From this, themes and sub-themes will emerge.

Applied in the pilot, rollout or governance stages, simple Root Cause Analysis tools such as these can help prevent or determine root causes of disengagement so you can take appropriate action. Good references to learn more about Root Cause Analysis tools include The Six Sigma Memory Jogger II or The Black Belt Memory Jogger. Happy sleuthing!