The ETTO Principle: efficiency-throoughness trade-off : why things that go right sometimes go wrong

Accident investigation and risk assessment have for decades focused on the human factor, particularly 'human error'.

Countless books and papers have been written about how to identify, classify, eliminate, prevent and compensate for it.

This bias towards the study of performance failures, leads to a neglect of normal or 'error-free' performance and the assumption that as failures and successes have different origins there is little to be gained from studying them together.