Efficiency–thoroughness trade-off principle

The efficiency–thoroughness trade-off principle (or ETTO principle) is the principle that there is a trade-off between efficiency or effectiveness on one hand, and thoroughness (such as safety assurance and human reliability) on the other.^[1] In accordance with this principle, demands for productivity tend to reduce thoroughness while demands for safety reduce efficiency.^[2][3]

The ETTO principle was formulated by safety researcher Erik Hollnagel in 2009.^[1]

In safety

The principle has been applied to analysis of behaviour and choices made regarding safety and risk. There are competing activities requiring time, which is a limited resource. In order to make time available for desirable activities, less time can be spent on preparation and planning, which affects safety. Most of the time the trade-off ends well, and the preferred or profitable activity proceeds without undesirable incident, which is why these trade-offs are so prevalent. Eventually luck may run out and something goes wrong. In hindsight it is often obvious when and where such trade-offs were made, and the consequences may be clearly linked to causes, but the trade-off seemed like a good idea at the time, and for as long as things kept going right.^[4] The principle of requiring "reasonably practicable" precautions in occupational health and safety recognises that such trade-offs must exist to allow economic activity to proceed, and puts the onus on the employer to assess the risk and take those precautions.^[5]

See also

• Project management triangle