Five Whys

Five Whys is a questioning technique that moves from a stated problem to more specific explanations by repeatedly asking why it occurred. The number five is a prompt to look beyond the first answer. It does not require exactly five questions or certify the final answer as a proven cause.

Take a damaged-delivery complaint. Why was the item damaged? It broke inside the box. Why? It moved around during transport. Why? The padding around it was too thin. Why? The packer was new and had not been taught the padding rule for fragile items. Why? New staff were allowed to pack on their own before finishing training. Each answer is a candidate connection until observations or records support it. If the returned packages show the damage came from rough delivery handling rather than from packing, continuing down this training branch would investigate the wrong mechanism, and the analysis should return to the first question with the delivery stage as a separate branch.

Write the evidence, uncertainty, and next check beside each answer. Ask what would contradict it and involve people who see different stages of the work. Stop and investigate when an answer is unsupported; split the analysis when several causes could contribute. Do not force a chain to end at a person or department.

The technique helps organize investigation but does not replace a timeline, process analysis, or a suitable test of an intervention. Agreement among participants is not independent evidence. After choosing an action, check both whether it was implemented and whether the relevant outcome changed under comparable measurement conditions.

Examples are illustrative.

References:

• ASQ: Five Whys