Wednesday, September 30, 2009

Corrective Action Request: Please Fix Your Typo!

One of my pet peeves is the corrective action request for a single incident, especially for a single part that was found to be non-compliant. Many of you have probably been faced with this request, or you've been the perpetrator of such an annoyance.

In analysing any processes, there needs to be sufficient data to determine the variability and know what the normal output of the process is. This is the foundational principle of Statistical Process Control and often considered the heart of any quality improvement method. Collect the data, analyse the patterns and make some improvements to affect the whole output of the process.

It doesn't need to be a manufacturing process solely. Data can be used to analyse almost any process, including administrative processes...even literary processes like authoring blogs. The analysis relies on the collection of data, not a single datum. No one can look at one piece of evidence and accurately speculate on the whole output, the whole "population" of a group. To do so is like creating stereotypes about people based on meeting one person in the demographic. For example, one red-headed person yells at you for stepping on his foot. From that single datum, you could erroneously suggest that all red-heads are hot headed and short-tempered.

Likewise, to have a single failure, it is impossible to determine the cause of the failure. Without determining the cause of the failure, any suggested correction or improvement would be shooting in the dark. Yet many customers demand a response for a single part failure.

Everyone makes mistakes. The important thing is to know if it's a pattern of mistakes. If so, then we can figure out a cause and a solution. If it's a one-time thing, don't be bothered. "Minor on the minors." If it's a repeat thing, be bothered. "Major on the majors."

There's an old story about the farmer and his wife heading home from church. The mule pulling the buckboard stops a mile from the church. The farmer climbs down from the buckboard muttering, "That's one." He cajoles the mule into moving again. After another mile down the road, the mule stops again. The farmer climbs down again, muttering, "That's two." The mule gets going once more, but stops after another mile. The farmer mutters, "That's three." He pulls his rifle and shoots the mule. His wife goes crazy, yelling at him about shooting the mule: "That's our mule. Now how will we get home. What's going to pull the farm equipment? How will we make the farm work? We can't survive this. What are you doing?!" The farmer stows the rifle away, muttering, "That's one."

It's not a problem till it's a pattern.

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