an exploration of 5 forms with examples
by Tom Curtis
• Created July 2010 by Tom Curtis
• All Pictures take by Author
• Blog: www.onimproving.blogspot.com
• Other Presentations: Onimproving on
Mistake Proofing is all around us whether we
recognize it or not. The purpose of this
document is to look at some of the common
ways it can be deployed and examples to help
begin to recognize and start to employ in our
spheres. This does not seek to be the last word,
but hopefully a door to seeing mistake
proofing in the world around us.
--Tom Curtis 2010
Forms of Mistake Proofing
May overlap or be used in combination
In some cases a mistake can be prevented.
This may include use of shape or size or
function. Classic examples in this space
include the different size of the diesel and
unleaded gas nozzles, or something that can
only fit in one way. This is sometimes
called poka-yoke. This form is most often
associated as mistake proofing.
Pausing or delaying techniques do not fully
prevent a mistake occurring, but rather force
an individual or group to stop and overcome
some hurdle to proceed. An example is a
computer program that asks “Are you sure?”
before executing a desired command. The
goal is that in being forced to stop a mistake
may be prevented.
In notifying the system or process lets us
know that something needs to be addressed,
but does not prevent us from continuing, like
in preventing or pausing forms. For this
type of proofing think of the gas light in
most cars. It lets us know that a mistake will
eventually be made (running out of gas),
but it is up to us as to whether we heed the
notice or not.
In minimizing it is realized that there may
be a mistake made, but that the damage can
be controlled. Think of a machine that shuts
down when it gets too hot. The machine does
get hot, but does not allow the motor to burn
out. There is some damage done, but the
greater damage is minimized.
Guiding or suggesting is similar to
notifying, in that it does not stop the process
and is a message from the process. It differs
in that there is not a mistake that will happen
if disregarded. An example is the please wash
your hand signs for employees that you
often see in public restrooms. We are
protected if we heed, but are not punished
automatically if we do not.