Five whys
Five whys is a root-cause technique: ask “why” a problem happened, then ask why again about that answer, repeating roughly five times until you reach the actual cause rather than a symptom.
Each “why” peels back one more layer of causation, so the technique works best on a specific, well-defined problem rather than a vague one. It’s cheap to run – no special tooling, just a team and a willingness to keep asking – which is why it shows up so often in lean and continuous-improvement practice.
Done well, it prevents recurrence rather than just patching the immediate issue, which saves the time and resources that would otherwise go into fixing the same problem again. Done poorly – stopping at the first plausible answer – it just relabels the symptom as the cause.
See how five whys applies inside a real incident root-cause analysis.