Research pick: Five whys failed M.O. - "Five whys: a possible path to failure"

The “five whys” technique is a problem-solving approach that involves repeatedly asking “why” to uncover the root cause of a failure. It is widely used in manufacturing, healthcare, information technology, aerospace and aviation, and in the service industries. However, it has limitations, not least a lack of understanding of how to use the approach correctly. Research in the International Journal of Six Sigma and Competitive Advantage has now looked at how the method can be used as either a superficial brainstorming tool or a rigorous investigative process and that understanding the approach in detail is essential to good quality control and safety in many different sectors.

The “five whys” is the modus operandi of many a root-cause analysis. It is a systematic approach that can be used to identify the causes of a given problem or failure so that a recurrence might be prevented. Matthew Barsalou of QPLUS in Manama, Bahrain, Beata Starzyńska of Poznan University of Technology in Poznań, and Maria Konrad of Spawmet Zbigniew Kaczmarek in Ostrów Wielkopolski, Poland, explain that the efficacy of the “five whys” method works by alternating between asking “why” and conducting empirical investigations to validate each cause identified. For instance, if a bolt breaks and the answer to the question “why?” is simply because it was a weak or faulty bolt, then simply replacing it with a stronger bolt may well fail to address the underlying issue if the true cause of the bolt’s demise was vibration in the system. The correct use of the “five whys” ensures that the underlying cause is found and mitigated.

The team has carried out a comprehensive review of the literature in this area and categorized the descriptions of the “five whys” problem-solving approach into three distinct groups. The first is the simplified approach that merely asks why without empirical evidence. The second is the empirical approach that requires actual investigation following each “why?”. The third is ambiguous use, where the item in the research literature was unclear as to the precise usage of the method. The researchers found that more than half of the research literature described the “five whys” as a simple brainstorming tool. Only a minority highlighted the necessity of empirical investigation to validate each step.

The team followed up their review by surveying organisations about their use of the “five whys” method. This survey vindicated the review findings to reveal that many organisations simply used the “five whys” as a brainstorming method rather than an investigative approach. However, they note that those organisations that used the method frequently were more likely to recognize the importance of thorough investigation to back up the answer to each question “why?”.

The problem that is obvious in retrospect is that the approach is being misused widely, leading to ineffective solutions and unresolved issues. Brainstorming alone is usually insufficient to identify the true cause of a problem, whereas empirical investigation after each “why” ensures solutions are based on verified causes, leading to more reliable and effective problem-solving.

Barsalou, M., Starzyńska, B. and Konrad, M. (2024) ‘Five whys: a possible path to failure’, Int. J. Six Sigma and Competitive Advantage, Vol. 15, No. 1, pp.19–32.