Lean Tool of the Month-Poka Yoke

Poka Yoke (Pronounced Poka Yokay) is quite literally, mistake proofing. A mistake proof is anything that prevents an error from occuring. One of the seven lean wastes is Defects or Poor Quality. Poor quality is a lean waste because it causes additional product to be manufactured or additional repetitions of the work process to be performed to achieve an acceptable result. This is waste. In an ideal lean world, we would do it right the first time, with no wasted effort or resources. So if poor quality is a significant issue in the lean waste stream, Poka Yoke is an effective ideal to help address it. There is no standard formulaic way to apply Poka Yoke, its simply the concept of something that prevents the mistake from occuring in the first place. Without even knowing it, we all have at least a dozen Poka Yoke that we interact with on pretty much a daily basis. Here are some examples that you may not have noticed.

All of these are Poka Yoke because they prevent us from inserting the plug incorrectly. A Poka Yoke does not have to a physical means of preventing a mistake. Ever order anything from the internet? or do your banking electronically?, or refill your prescriptions over the phone? There are Poka Yoke's in those systems that prevent the order from being placed without your authorization (that 3 or 4 digit number they always ask us for from the back of the credit card), or the account number for our savings account or refill number for our prescriptions. All of these systems have a poka yoke to prevent the vendor or the client (us) from making a mistake.

So the next time you're grappling with a tough quality problem in your process, don't dismiss a poka yoke just because you're working on a transactional or back office process where there's no physical control or prevention that can be easily done. Plenty of electronic business systems give the user some ability to require certain information in order to process a transaction to the next step. That's a poka yoke.