“Learning cannot be disassociated from action.”

-- Peter Senge, The Fifth Discipline

“The most important measures are both unknown and unknowable.”

-- W. Edwards Deming, Out of the Crisis

 

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How Do You Find Root Causes? by Kevin McManus

Organizations use a variety of approaches to find the root causes of problems. The most popular, formal approach is probably the fishbone, or Ishikawa, diagram, which has been in use for at least 25 years. The recent growth in popularity of lean manufacturing and six sigma methodologies has helped bring the ‘5 Why' technique more into vogue, even though this tool also is at least 25 years old (it was part of the Toyota Production System model). Unfortunately, few organizations truly master the skills required to (1) find the root causes of their problems and (2) implement fundamental system changes to address those causes. In turn, they continue to face the same issues day in and dayout – their problems keep coming back.

This article summarizes the similarities and differences between five common techniques that are used for problem solving through root cause analysis:

5 Whys

Kepner Tregoe Problem Analysis

Fault Tree Analysis

Change Analysis

Fishbone Diagram

TapRooT® RCA advantagesThese techniques are discussed in the paragraphs that follow. A summary of the eight advantages provided by the TapRooT® root cause analysis process over these techniques is then presented. You get to decide which approach might work the best for you.

Technique Name: 5 Whys

Features: From my perspective, the Five Whys represent more of a conceptual, as opposed to a systematic, fact-based approach, to root cause analysis. It was adopted from the Japanese approach to management, most notably practiced by Mr. Shingo, who would use the five whys on the production floor when he would tour manufacturing sites. In essence, Mr. Shingo would continue to ask why five or more times to get to the true cause of a problem, with his questions being structured to help lead the employees he was talking to towards the problem's source.

Advantages : If a person knows how to ask good, successive ‘why' questions, and is able to ask them of the right people, he or she will find at least one root cause for a given problem. This approach takes little time to perform – as few as five minutes can be used to perform a five why analysis – and does not require the use of special software, flip chart paper, or reading materials. If it is performed repeatedly with the same group of people in a sound manner, its use can lead to a new way of thinking amongst those people that have been exposed to the tool's use.

Disadvantages : The 5 Why approach normally leads to the identification of just one root cause for the problem in question. You will need to go through the ‘5 Why' process several times for a given problem in order to ensure that all root causes are identified, and being able to do so effectively requires even more skill of the part of the question asker. It also does not necessarily point the problem solver towards the generic causes of similar problems.

This approach requires significant skill in order to learn how to ask the right why questions – the five why technique is not as simple as asking ‘why?' alone five times. While the use of this tool will lead to the definition of a root cause that is also a change that is needed (a corrective action), it does not often result in a corrective action that is well developed and defined. Most people fail to gain much success when using this tool simply because they cannot develop the ability to ask good ‘why' questions in succession, even though Mr. Shingo was quite skilled at doing so.

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Technique Name: Kepner Tregoe Problem Analysis

Features: I attended a five-day KT training course in 1990. The training did cover root cause analysis in a sense, but more in the form of general problem analysis. The key components of the KT process include problem analysis, potential problem analysis, situation analysis, and decision analysis. Problem analysis contains a form of root cause analysis, but is based largely on the ‘is / is not' tool that is more similar to the Taproot Change Analysis process. The Decision Analysis tool is a great tool, and I still advocate its use today, but it focuses on teaching people to evaluate possible improvement options in a systematic, fact-based manner, as opposed to finding root causes. Situation Analysis is used to assess the risk associated with possible improvements, and Potential Problem Analysis looks at the possible repercussions of failing to make a change.

Advantages : Like TapRooT®, if the user has performed a good problem investigation and has collected a

lot of information (especially data), they can find the causes of the specific problem being analyzed, even though they may not be specifically called root causes. To me, the Decision Analysis tool is one of the best out there for evaluating improvement options (possible corrective actions).

Disadvantages : Good information and a formal evaluation process helps keep the user of any of these tools from focusing too much on blaming people, but the tools can be time consuming to use and are not as functional as TapRooT® is in terms of getting to generic causes. I also question whether or not these tools can help you get to the true system problems that are causing given incidents to occur (which the TapRooT® process is designed to help you do). Well-rounded corrective action development is really not a focus of these tools as I remember them.

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Technique Name: Fault Tree Analysis

Features : My perspective of fault trees is that they encourage the user to (1) ask the five whys multiple times for a given type of problem and (2) evaluate several possible problem causes on one diagram (similar to the manpower, methods, materials, and machines boxes on a fishbone diagram). Like the other common root cause analysis approaches, fault trees tend to be a predominantly opinion-based tool, in that there are no predetermined questions that are used to help you create the branches of a given tree.

Advantages : From my perspective, I prefer fault trees over fishbone diagrams because their design allows four to five levels of ‘why' to be identified for a given problem, if the users are willing to exercise a high level of discipline as they draw their charts. I find them to really be useful for troubleshooting reoccurring problems, such as quality defects, because such problems tend to have a common set of causes and sub-causes. When used in this manner however, a fault tree essentially becomes analogous to the TapRooT® Equifactor tree which is used for equipment troubleshooting.

Disadvantages : Fault trees typically fail because (1) people do not use them in a disciplined manner to develop multiple problem causes at each level, (2) multiple levels of potential causes exist to be sorted through for each problem type, and (3) they are opinion driven. They often tend to be a blend of a cause effect diagram and a flow chart, but in such cases, the user can easily get lost and not arrive at any particular root cause. Also, a well-developed fault tree often leads the user to discover that the same management systems (such as poor training, employee turnover, weak communications, and poor procedure design) are at the root of their problems (which is similar to the TapRooT® generic causes). In turn, a well-designed fault tree will lead you to the TapRooT® basic cause categories, but rarely to the comprehensive mix of TapRooT® root causes.

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Technique Name: Change Analysis

Features : I have not seen change analysis called out as a tool for finding root causes by itself. The KT ‘is/ is not' problem solving tool is the closest thing to change analysis that I have seen. As I stated above, this KT tool is in essence the same as the TapRooT® Change Analysis tool.

Advantages : It is always useful to compare what should have happened to what did happen when analyzing a problem, but this effort alone will not lead you the root causes of, and corrective actions for, preventing the problem in the future.

Disadvantages : The Change Analysis tool appears to be limited to comparing what should have happened to what did happen, and in turn does not lead you to the actual root causes of, and corrective actions for, preventing that problem in the future.

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Technique Name: Fishbone or Ishikawa Diagram

Features : This tool is perhaps the oldest, and most well known, tool for conducting a root cause analysis. In its most common form of use, the user attempts to define multiple possible causes for a given problem in the four areas of manpower, methods, materials, and machines. The five why technique is often used with this tool to construct the bones of the chart, with the answer to each why resulting in a new branch being created off of the previous one that the question originated from.

Advantages : This tool is better than nothing, and serves as a useful tool for getting individual opinions onto a sheet of paper so that everyone involved can talk about them and suggest additional possible causes. In a lot ways, it is similar to identifying the conditions for a snapchart, but that is where the comparison ends.

Disadvantages : This is an opinion-based tool, and its design limits the user's ability to visually define multiple levels of ‘why' answers unless the paper that is being used is really large. Worse yet, opinion (voting of some form) is normally used to select the most likely causes from those listed on the diagram. Teams are then encouraged to test different countermeasures for the selected causes to see if the problem goes away, which can be both time consuming and costly. The tool also does not focus on finding and eliminating generic causes.

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TapRooT® Advantages

Here are eight primary reasons why I feel the TapRooT® process is superior to any of the above listed tools:

•  It is a closed loop process in that it uses the snapchart for problem definition (define), the root cause tree and trending for root cause identification (measure and analyze), and the corrective action process to define well-rounded problem solutions (improve).

•  The snapchart is time-based, in that it shows the sequence of events leading up to and following a given problem. This tool helps the user identify a more complete set of events and conditions that led to a given problem's occurrence.

•  The process is based on a set of well-developed operational definitions and questions, which are based on years of research and application, and which discourage the user from relying primarily on their opinions when selecting a root cause or causes.

•  The process encourages the identification of generic causes, which if corrected, will prevent similar problems from appearing in other parts of the organization or in other products or services in the product / service line.

•  The process software contains hundreds of possible corrective actions that have been used by hundreds of companies to correct and prevent the problems that result from both singular and generic causes.

•  The process is grounded in human factors theory, which supports the fact that people are the key to organizational success and most often the source of most problems due to the design of the systems and processes they use and the decisions they make as they do their jobs each day.

•  The software's design and content encourages and enables the individual problem solver, or a team of problem solvers, to keep their efforts focused and organized due to the existence of the dictionary, corrective action helper, a highly visual problem definition (snapchart) and root cause analysis process, and the linkages between the snapchart causal factors, the root causes selected, the identified corrective actions, and the assortment of incidents analyzed.

The results that you get from using this tool versus the time invested to use it will almost always far outweigh the results you will get from the time invested using any of the above tools – the time required per tool application is not much, if any, greater, and the quality of results is far superior. In most cases, a couple of hours of use with most of the above tools would only give you a list of possible causes – in the same amount of time, the TapRooT® process will give you a clearly defined problem, a focused set of root causes, and a sound mix of corrective actions.