Guest Post: Preventing Mistakes - Not Just Chump Change

Companies just seem to love big initiatives.  The thinking perhaps goes: If we hire an expensive consulting firm, we can transform the way we do business, we can start big projects, we can give out lots of new titles, and at the end of the year we can analyze our results and see if we had a gain.

Or...we can do some simple mistake-proofing and pick up the change that’s lying on the floor.

When we look at our value stream, we want to see an unobstructed flow, without detours, hiccups, or reversals.  When we create defects, we throw a monkey wrench into the works and our flow is interrupted.

To make the situation worse, many of us tend to institutionalize our waste.  We create quality systems to document our defects.  Some companies have even created re-work departments.  Talk about non-value added!

I need you to change a bit of your traditional thinking. In order to implement successful mistake-proofing, we have to accept the reality of human error. We have to acknowledge that humans (and machines) will make mistakes.  Once we accept that fact, we can set about putting things in place that will prevent the error or defect; but if we don’t embrace the reality, we are doomed to repeat the waste over and over again.

One of the exercises I like to do is have folks make a list of 10 recent defects in their workplace. We then target one from that list and do a thumbnail cost analysis along with a list of all the aggravations associated with that problem.  It’s quite eye-opening.

A frequent contributor to the list is setup errors.  After all, when you set up a job incorrectly you typically make the entire job wrong, but the root cause is often something simple.  Someone entered an incorrect date code or someone used the wrong product label, those types of things.  (I have seen simple order entry errors cost upwards of a million dollars when a large order had to be scrapped.)

Next, I ask “What did your company do to make sure it never happens again?”

“Well, we had people work overtime to re-work the product so we could get the order out and satisfy the customer.  We also issued a stern e-mail telling all the supervisors to keep a closer eye on things and to try harder.”  That accomplishes little.

Do a gemba walk and take a close look at how much time you are spending fighting fires.  Look at what your supervisors are doing at the moment.  Are they facilitating or firefighting?

Rather than accept the situation, institute a strong mistake-proofing program and put things, lots of things, in place that will eliminate the opportunity for the error.

Simply put, a mistake-proofing device is something that makes it impossible for the error or defect to occur.  It could be a mechanical gizmo, a change to a form, or a change to software.  The possibilities are limitless.

Toyota has an average 14 mistake-proofing devices at EVERY workstation. You should, too!  Go ahead and take away the opportunity to make a judgment error, an identification error, an entry error – the list goes on forever.

There are number of things that contribute to effective mistake-proofing in the workplace:

  • Accept that errors are inevitable and that we will implement real devices to prevent the error.
  • Educate our workforce in the concept of effective mistake-proofing.
  • Avoid blame.  Ask ourselves, “Have we provided the worker with all the tools necessary to ensure success, or are we setting them up for failure?”
  • Use a standard method when mistake-proofing.  I like using a source error chart.  Don’t rush the investigation process.  Take a little time to get it right.
  • Use small cross-functional teams in mistake-proofing events.  I like groups of six or seven people and would normally devote four hours or so for a particular defect.
  • Don’t get too hung up on the root cause.  I know this may sound sacrilegious in quality circles, but sometimes the root cause is simply “I forgot.”  By accepting the fact that people forget things, we can look for a device to help us remember.

After you put your device in place, keep looking for more opportunities.  I don’t usually recommend you look for “What if?” scenarios for something that might go wrong.  I like to look at the big pile of things that actually did go wrong and caused us grief.  There is plenty of action without looking for something that might happen. For instance, look at the re-work area and strive to eliminate it.

If something happened once, it’s very likely to happen again – and again – and again. So don’t put up with it. Use mistake-proofing to pick that change up off the floor.

This post was written by Sam Hoskins, CSSBB, MS, president of MistakeProofing.Net. Sam is an experienced hands-on mistake-proofing trainer and facilitator, who has conducted dozens of events for a diverse range of industries such as explosives manufacturing, processed food companies, welding and fabricating shops, and healthcare.  He learned lean and mistake-proofing while at the Ensign-Bickford Company and authored the mistake-proofing portion of their successful application for the 2001 Shingo Prize.  In addition to mistake-proofing, he is currently conducting Lean 101 training for a variety of companies through Parkland College in central Illinois. You may reach Sam at

There are 2 Comments

Sam Hoskins's picture

Yes, we sure have a lot of room for improvement. So often, we accept in-house defects, problems, and errors as being somewhat normal. Then we wind up spending our time engaging in non-value added firefighting.

Thanks for the note.


Chris Paulsen's picture

Sam-interesting post. 14 poka-yokes at each workstation is amazing. Just think about how many work stations they have at just one of their plants....That illustrates how much we can pick up our game. Thanks for sharing.