5-Why Weaknesses

As with all tools, 5-why analysis has its share of weaknesses. Find out more about its limitations, and how to maximize the potential from 5-why. The final part in a four-part series on 5-why.

More information: An Introduction to 5-why, 5-why Analysis using a Fishbone Diagram and 5-why Analysis using an Excel Spreadsheet Table

5-why analysis isn’t perfect. In fact, it’s known to have produced very strange, skewed and biased conclusions, depending on how it’s used.

One of the major problems is that conclusions reached from 5-why could have widely different root causes, depending on the analyst’s point of view and experience. Those who are biased can skew the results even more by producing an analysis in their favour, while disregarding the other facts present.

Some people may not take the analysis far enough. There are many cases where we have to ask “why” more than five times in order to find out the true root cause, especially in complex and convoluted problems.

The final problem to befall the 5-why analysis is human in nature: since 5-why is qualitative, the conclusion is obviously subjective and open to interpretation.

In smaller, low-stake projects, the flaws tend to be minimized because the temptation to skew results is lower. Conversely, high-risk projects increase the possibility that 5-why analysis will be biased and incorrect.

Despite its shortcomings, there are ways to minimize its flaws, so you can minimize the risk of a faulty root cause while still cultivating the power of this tool.

Group Work

To minimize the risk of a biased conclusion, it would be wise to form a group consisting of subject-matter experts and those involved in the actual issue. By mixing both, it ensures that those involved are able to provide first hand accounts of the situation. Subject-matter experts help to minimize the risk of a one-sided assessment, while still having the knowledge to make a fair analysis.

Each individual needs to make their own fishbone diagram first, and come up with their own conclusions and rationale on what the root causes are. The group will then reconvene and each individual will be given the opportunity to present their findings and supporting reasons.

Once each individual has done so, a vigorous group discussion will help to prioritize the fixable root causes.

Split into its Components

In more complex problems, we may need to split the problem into smaller components to help to focus on the main issues. To do so, you can use one of the major cause categories you learned about in the fishbone diagram analysis.

But at the end…

5- why analysis is still an indispensible tool for your root cause analysis. With some foresight, you can overcome some of its weaknesses to come up with solutions which truly tackle the root-cause of a problem.

You can read more about horenso (effective communication), PDCA (Plan-Do-Check-Act), mieruka (use of visuals) and 5-why here, which also includes articles, tutorials and downloadable diagrams, sheets, PDFs and other tools to help you implement kaizen and bring the competitive edge of the Toyota Way to your manufacturing or service-industry project or organization.