The Joy of Slack

Robert L Wears, MD, MS, PhD

“Slack.  The term reeks of inefficiency.”1  It suggests a sloppiness, a looseness of coordination, a falling behind the tempo of operations.  “Slackers” are generally not among those whose performance we praise or wish to emulate.

Over 20 years ago, Paul Schulman argued for the counterintuitive virtues of slack1.  Slack can take different forms.  Resource slack is a surplus of equipment, supplies, or personnel relative to current demands.  It can be viewed conventionally as non-productive waste, or alternatively as a hedge against unexpected demands, a buffer against external or internal shocks.  Temporal slack is a bit of extra time.  A nice example of temporal slack is the “scheduled hold” in NASA’s countdown procedures; NASA’s engineers recognized that although they could not predict precisely what problems they would encounter during a countdown, they could be reasonably sure they would encounter some; so they provided additional time in which to address them rather than have an unexpected “glitch” cause them to miss a launch window.  Temporal slack can be viewed either as unnecessary waiting, or as an opportunity to consolidate resources or address disturbances.  Procedural or control slack involves the under-specification of either processes or authority.  It can be viewed as ambiguity and lack of control, or as potentially useful flexibility and protection against the dysfunctional potential of centralized authority2.  Finally, conceptual slack is a heterogeneity of perspectives on a system’s state, functions, and environment.  It can be viewed as confusion and conflict in shared understanding, or as maintaining a “requisite variety” of viewpoints, a protection against hubristic “groupthink”3-5.  Sadly, Schulman’s insights have been all but forgotten in the Cartesian-Newtonian vision of a progressively more perfectable world6.

Slack in its many varieties serves to loosen coupling and so enhance safety7.  It would seem a necessary but not sufficient resource supporting resilient performance.  Unfortunately, slack is under tremendous pressure, especially in healthcare as these systems are doubly beset by economic pressures and by the rationalising impulse to drive out waste and to “engineer” everything – “to establish once and for all consistent, unambiguous guidelines and to tolerate no competing organizational perspectives.”1  Resource and temporal slack are threatened by the drive for greater economic efficiency, while control and conceptual slack are threatened by the hegemonic agenda of technical rationality8.  The voices crying out for a variety of “improvement” efforts – the measure and manage orthodoxy of Lean, Six Sigma, TQI, etc. – are popular, loud, and increasingly bristling with external power, leaving advocates for slack as lonely voices crying in the wilderness.

But the erosion of slack is a grave threat.  Slack is loosely analogous to cash reserves in finance, or carrying capacity in ecosystems; one can temporarily improve performance by borrowing from these reserves, but depleting them too far not only drives the system to the point of collapse, but also impoverishes its ability to continue and recover after collapse9.

To have safe and resilient systems of care, we will have to learn how to value slack, and in this valorization to take a take a “long view” – because in the long run, things that never happened before happen all the time10.  Aaron Wildavsky uses the example of Mario Puzo’s Godfather, whoworked very hard at doing favours for people, even though he expected no immediate return or even any return at all.  He notes the Godfather wished “to have others beholden to him in diverse and unspecified ways, precisely because he knows that he won’t know in advance who he will need or when or for what purpose”11.  By accumulating nonspecific resources – building slack — he increases the odds he can meet unexpected challenges.

Unfortunately, when confronted with internal problems or external threats, many managers respond with “threat rigidity” – actions that restrict resources and tighten control, ironically reducing slack at just those times when it is most needed.  When greater performance (faster, better, cheaper) is needed but when achieving it imposes demands on limited slack, it would be better to find ways of increasing slack before pushing for higher performance.  The inevitability of tradeoffs among competing dimensions of performance12 underscores the need to identify and preserve slack.

What we need now are a few good “partisans of the neglected perspective” who can “know that they won’t know” and so act to accumulate and preserve slack.  To follow the cheers and high hopes that dominate conference proceedings, consultants’ pronouncements, and large parts of the ‘improvement’ literature is to engage in self-delusion and to risk catastrophe, because ultimately, reality inevitably trumps utopian scientism, and “nature cannot be fooled”13.

References and further readings

  1. Administration and Society 1993;25(3):353 – 372.
  2. New Technology and Human Error. Chichester, UK: John Wiley & Sons; 1987: pp 111 – 120.
  3. Organization Science 1991;2(1):1 – 13.
  4. Qual Saf Health Care 2003;12(6):465-471.
  5. Cybernetica 1958;1:83 – 99.
  6. Drift into Failure:  From Hunting Broken Components to Understanding Complex Systems. Farnham, UK: Ashgate; 2011, 220 pages.
  7. Normal Accidents:  Living With High-Risk Technologies. New York, NY: Basic Books; 1984: pp 62-100.
  8. The Reflective Practitioner:  How Professionals Think in Action. New York, NY: Basic Books; 1982: pp 21 – 69.
  9. S-Shaped Growth, accessed 25 January 2014.
  10. The Limits of Safety:  Organizations, Accidents, and Nuclear Weapons. Princeton, NJ: Princeton University Press; 1993, 286 pages.
  11. Searching for Safety. New Brunswick, NJ: Transaction Books; 1991, 254 pages.
  12. Intelligent Systems, IEEE 2011;26(6):67-71.
  13. Report of the Presidential Commission on the Space Shuttle Challenger Accident:  Appendix F – Personal Observations on Reliability of Shutte. Washington, DC: US Government Printing Office; 1986, http://history.nasa.gov/rogersrep/v2appf.htm, accessed 22 October 2013.