Saturday, May 17, 2008


Cool Tools has an interesting review of Mistake-Proofing: Designing Errors Out and, as is common with most book reviews on that site, provides some marvelous excerpts. My favorite one is a reminder of many a do-it-yourself project:

The best way to ensure the detection of a mistake is to make sure that something in the environment makes it very obvious that one has been made. A good example of an environmental cue is the inevitable "extra" parts that remain after a do-it-yourself repair project. These parts make it very clear that you have not reassembled the item correctly.


Larry said...
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Larry said...
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Larry said...

When I was doing, or was in charge of doing system design work, I (sometimes against advice) always tried to design things in the code to catch errors.

The conceptual model was something I was taught in elementary school--to "check my work" either by solving the problem a second way, by reversing the solution, or by using something like "casting out nines".

As a minimum, I insisted on range checks or reasonableness tests.

I see lots of silly errors that could have been caught.

Larry said...

Oh, and on the "spare parts" thing...

When assembling a kit I go through the parts list and count everything, setting aside "overs" in a suitable container apart from te working stuff.

And when I used to overhaul carburettors and such as each part in the original was replaced with a part from the kit, I set the replaced part aside.

Kind of like the sponge count in an operating room. I guess.

I wonder how many know what a carburettor is.

Michael Wade said...


Lately, I've started following your "spare parts" advice and it has been so helpful I'm embarrassed to think how long I didn't follow that routine.

Jeff said...

I know what a carburettor is - or carburetor as we spell it on this side of the pond. I also know my way around a set of drum brakes, how to set points in a distributor and check the timing of the engine afterwards. Anytime I made repairs, I placed the parts in a basket. When I reassembled, I often ended up with a few spares. Car still ran right - I wondered if the darn thing had been built correctly in the first place.