Everyday Lean: Website Data Entry
I saw an example of error proofing when I was registering on Art Smalley's Lean Website. Like many websites, it makes you enter your email address twice. If you type it incorrectly one time, the system will flag you and prompt you to re-enter it quickly. The odds of you typing it incorrectly twice are less than the odds of mistyping it just once.
That is, unless you're lazy and “cut and paste” the first email address into the second box. But, I guess it shows that not all error proofing attempts are 100% effective. Think about your error proofing and think about how people might circumvent the error proofing.
I'm sure a website designer would say “but you're not supposed to cut and paste.” Think about the way employees are co-workers are “not supposed to use” your error proofing, your machines, etc.
Also, I've seen that “double entry” method applied in a less “everyday” example. I've seen a data entry operation, where they used to have a second person inspect the first person's data entry, to make sure info was correct. They changed their software so that the second person re-enters a few key pieces of data. If there's a mismatch between the first and second person, the system flags it. They found the “second entry” was actually faster and more effective than manual inspection. Go figure!