Variation is Normal

Why are we always so surprised when something goes wrong? If we understood the processes we manage we should be expecting it.
W. Edwards Deming, and Walter Shewhart before him, based their ideas on the fact that there is variation in any process. I was reminded of this when listening to a radio programme on animal behaviour, when the speaker asked why we expected all animals in a species to behave the same way when no two humans will. We assume “personality” is a purely human trait – but it’s not – in all species, variation is the norm. Which is where I was reminded of Deming and Shewhart’s teaching. It was the teaching that Deming took to Japan after WW2, the teaching that led to Japan becoming one of the world’s biggest economies.

If we can control every variable in a process, we can eliminate variation and get 100% predictability. But can we ever get to that situation? I doubt it (though I’ll concede it may be possible in extreme situations). When we design (as an engineer) we address tolerances, knowing there is a limit to precision. When I worked for Rolls Royce (its aero engine division), I was introduced to the concept of the MMC and LMC (maximum/least material condition) – identifying when the tolerance on one dimension (or part) would affect the acceptable tolerance of another. In effect, with precision fits, don’t be surprised if two parts meant to fit together, each manufactured within its specification, don’t do so every time. Sometimes the precision we need is greater than the precision we can make (economically, at least) so there needs to be an acceptance that we will sometimes get mismatch.

Transfer that understanding to business processes and we begin to see that we should expect mistakes; nobody will perform any task identically to anyone else, nor will the same person perform a repetitive task identically each time. Most of the time, for a well designed process, the variation is not significant; that doesn’t mean trying to define every step in minute detail, for that just raises our expectations of unattainable perfection. Rather, understand the process; know where variation is unimportant, where it is important and establish means to identify critical deviation. Moreover, understand that we will often overlook seemingly innocuous interactions that are actually significant. Prepare for failure (which doesn’t mean planning to fail) – know how to identify and respond. And, above all, don’t be surprised. Variation is normal.

(Posted as a blog 5th January 2015)