We own a washer and dryer combo unit made by a large home appliance manufacturer--let’s call them “Maytag.” The washer and dryer are in the company’s Neptune series. We’ve had them for about seven years and they’ve worked flawlessly, until recently.
About four months ago the washer started making an awful squealing noise when it went into the spin cycle. No problem, I thought. We have an extended warranty. I’ll just call the friendly Maytag repairman.
I woke up yesterday morning at 6 a.m., downed a glass of juice, showered, got dressed, grabbed my briefcase, and ran out the door. I arrived at the office at 7 a.m. Waiting for me were nearly 50 e-mails; a couple of them were junk, but most were from actual humans to actual, little ol’ me. When did I get so popular? Soon thereafter the phone started ringing--advertisers, subscribers, contributors, vendors, trade partners, etc., etc., etc. By 7:30, I was already way behind.
I liked the way Craig Cochran discounted or lessened the credibility of the 5 Whys (“Don’t Fail Your Customers With the 5 Whys,” February 2009). He provided excellent rationale for its limitations. His alternatives were good; however, I do not believe they can replace Ishikawa’s use of the fishbone technique. While with IBM, I had a class in defect prevention using the fishbone technique followed by action teams to remedy candidate causes with a resolution to each of the viable candidate causes.
As Davis Balestracci frequently emphasized in his column, “RealWorldSPC,” published in Quality Digest for four years, it is fundamental to understand the context of the data before you begin to do any computations. It is the background for your data that determines how you should organize the data, how you should analyze the data, and how you should interpret the results of your analysis. Once you ignore the context, you’re like a train that has gone off the track, with the inevitable result.
Suppose you had 16 months of data on an important process (as plotted on the run chart seen in figure 1). For improvement purposes, an intervention was made after the sixth observation to lower this key process indicator. This intervention is equivalent to creating a special cause for a desired effect.