The 5 Whys technique in root cause analysis
The 5 Whys is one tool within root cause analysis (a toolbox for working out why a failure happened): ask why repeatedly until a cause cannot be explained any further.
Remember
Keep asking why about each answer until a cause cannot be explained any further, which is usually a system fault that can be changed rather than a person to blame. The number five is only a guide.
Think of the 5 Whys as a persistent toddler asking 'but why?'. You state the problem, ask why it happened, then ask why again about each answer. You stop when you reach a cause that cannot be explained any further.
A patient is given a drug they are allergic to. The allergy was not written in the file because the note went into the wrong patient's file, which happened because that file was kept in the wrong place, and that traces back to a filing system that could not cope with so many patients. The root cause is the filing system, and that can be fixed.
The real explanation is rarely the first one. Adverse events (injuries caused by medical management rather than by the underlying illness, that prolong hospital stay, cause disability, or both) usually result from a chain of failures in the system. In an investigation, stopping at the first superficial explanation rather than the system cause is called premature closure. The shift is from blaming individuals to asking why the system allowed the error.
Latent failures are conditions built into the system. They make active failures more likely, and active failures are the acts that directly lead to harm. Fixing latent failures is second order problem solving: it takes longer, but it is a longer-lasting fix that reduces the chance of the error happening again.
Other tools do different jobs. Timelines compare actual with expected care, and a fishbone diagram groups causes into categories to prompt discussion. Plan-Do-Study-Act cycles test a change (plan it, try it, study what happened and act on the findings) and improve a process once the problem is understood, but they do not trace the cause of one failure. Only the 5 Whys works by repeated questioning.
Key facts
- Method
- state the problem, ask why it happened, then ask why again about each answer until a cause cannot be explained any further.
- Aim
- to move attention from who made the error to why the system allowed it.
- How many whys
- the number five is only a guide.
- Final cause
- the last cause is usually a fault in a system rather than in a person.
- First and second order
- a first order solution is a quick workaround for the symptom that leaves the cause in place; second order problem solving is a slower fix of the root cause.
- Plan-Do-Study-Act
- a cycle that takes place around a change, in which you plan it, try it, study how it went and act on that to improve it.
Exam traps
- A fishbone diagram sorts possible causes into categories such as people, equipment and environment, but it does not reach one root cause by repeated questioning.
- A clinical audit measures practice against a standard and shows where care falls short, but it does not trace one adverse event back through its causes.
- Judging individuals against professional standards decides who is accountable, but it does not follow the chain of causes down to a system fault.
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