Lean MetricsOne of the key principles in lean manufacturing implementations is to “make it visual”.

The premise is that anybody should be able to understand the current status of a process at a glance.  Any out of standard conditions should be immediately obvious, so they can be rectified quickly.

One of the popular ways to implement this is to erect visual management boards that display charts and graphs.  The team can review these key performance indicators and see where they need to take action.

This is a key part of the lean process “plan, do, check, act”.

However, there is an inherent danger in managing processes this way.  As Peter Drucker once said “what gets measured, gets managed”.  This is certainly a very accurate observation.  The problem occurs when managing lean manufacturing measurement becomes the end goal and the team lose sight of why the metrics matter.

“What gets measured, gets managed”

~ Peter Drucker

To explain this further, lets look at an example.

Safety Metrics

A manufacturing company decides that they are going to roll out some ergonomics training to all of their employees.  This training is designed to make employees aware of awkward postures that they should avoid during the working day.  The thought behind it is that by reducing their exposure to uncomfortable working positions, workers will be more productive and suffer fewer injuries.  After all, safety is one of the key initiatives in lean.

In order to manage the delivery of this training, the management set a deadline when everyone must have completed the training.  They also set a target of 95% attendance, to allow for the inevitable holidays and sickness that will occur.  They decide to have a weekly meeting to review their lean metrics dashboard for progress on this goal.

Can you see the problem with this scenario?

Inevitably what happens during the weekly review is that an updated graph is presented showing the attendance rate for the training.  If the team are on or above target, everybody gets a warm feeling and moves on.  If the team are below target, a discussion about poor attendance or cancelled sessions probably ensues.  An action might be recorded for somebody to go away and try to correct the situation.

The problem here is that the metric, which is designed to promote the correct behaviour, is too far removed from the original problem.  The focus has changed.  Remember the idea was to reduce the number of ergonomics related injuries, but somehow this has been turned into a time and attendance problem.

Surely it would be better to walk the process and identify specific ergonomic issues that could be addressed.  This would very likely be quicker to implement and achieve better safety results.

Now this isn’t to say training isn’t important, or it doesn’t work.  It also doesn’t mean that visual management and metrics are a waste of time.  It is just a cautionary note that it can be all to easy to focus on chasing the numbers, instead of addressing the true root cause of the problems.

Some might say that this example is exaggerated. All I can say to that, is I have been in numerous situations where this has happened.  Others have discussed this problem here, here and here.  I would also point out that if left unaddressed, this can become a cultural issue.  By that I mean that the default behaviour at the lean metrics board becomes one of achieving the metric at whatever cost.

Chasing Lean Metrics Examples

Other examples of missing the point caused by chasing metrics are:

  • Not booking scrap until the next day to make the previous month’s numbers look good.
  • Transacting production from weekend overtime into the previous week to make the productivity look better.
  • Removing operator break times from availability calculations to improve OEE scores.
  • Closing a corrective action because a purchase order has been raised.  This is done to improve the closure rate, even though the issue hasn’t yet been fully resolved.
  • Not recording a failure at inspection because it was a simple fix. This inflates the pass rate and prevents the root cause being addressed.

What do you think?

Is this a problem you have encountered with lean metrics in manufacturing?

Which common manufacturing metrics are particularly prone to being chased in your experience?

How have you handled this problem?

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