Finding the actual cause.
WHY IT MATTERS
Addressing symptoms guarantees recurrence.
WHAT TO DO FIRST
Establish what actually happened, factually.
WHAT TO GATHER
What was observed When What was different from normal What the sequence was
WHAT TO AVOID
Starting from a theory Accepting the first explanation
WHY THE FIRST EXPLANATION IS SUSPECT
It is usually the most visible factor, not the cause.
WHAT ASKING WHY REPEATEDLY DOES
Moves from symptom toward cause.
HOW IT WORKS
For each answer, ask why that happened, several times.
WHAT EXAMPLE LOOKS LIKE
The order was wrong, because the details were entered incorrectly, because they were taken by telephone without confirmation, because there is no confirmation step.
WHAT THE ACTUAL CAUSE WAS
The missing confirmation step, not the person.
WHAT TO BE CAREFUL WITH
Stopping at human error.
WHY
It is never the end of the chain.
WHAT CATEGORIES TO CONSIDER
People and training Process and method Equipment and tools Materials and inputs Environment Measurement
WHY CATEGORIES HELP
They prevent fixating on the first idea.
WHAT TO TEST
Whether the proposed cause explains everything observed.
WHAT TO DO WHEN IT DOES NOT
Keep looking.
WHAT TO IMPLEMENT
A change that prevents recurrence, not a reminder.
WHAT TO VERIFY AFTERWARDS
That it stopped happening.
