Erik Hollnagel

Ph.D., Professor, Professor Emeritus



ETTO (Efficiency-Thoroughness Trade-Off) must be balanced by TETO (Thoroughness-Efficiency Trade-Off).

To make a trade-off between efficiency and thoroughness (ETTOing) in order to get through the work-day is normal, necessary, and useful. It is, however, not sufficient to be able to do something or to respond to the actual; it is also necessary to consider if anything unexpected may happen in the future (near term or far term). In other words, efficiency in the present presupposes thoroughness in the past, which paradoxically means that thoroughness in the present is necessary for efficiency in the future.

The ETTO principle therefore requires a symmetric TETO or Thoroughness–Efficiency Trade-Off principle. The practical question is when one should put the emphasis on efficiency and when on thoroughness. For an organisation that question may not be too difficult to answer, since there are clear differences between the day-to-day operations and functions such as supervision, and learning. It is practically a definition of an organisation that these functions can be assigned to different parts or to different roles. For an individual it is more of a problem, since it is impossible literally to do two things at the same time. For an individual, the ETTO–TETO balance therefore becomes an issue of scheduling various activities, and of creating time enough for reflection. Individual intentions to maintain a balance, to be thorough as well as efficient, may nevertheless easily run foul of time pressures, information push, and information input overload and must therefore be supported by the organisational culture.

In Resilience Engineering terms, the ETTO-TETO balance corresponds to need to be able both to respond and to anticipate.