Chaos Re-visited -- Dickeson
But, if we're working an 8/5 production plan, can we change to 16/5 or even to 24/7? But how shall we increase sales volume? Cut prices? Despite what my columnar colleague the "Mañana Man" says to the contrary, cutting prices may be the route to making a lot more profit. Ask the folks at WalMart. (Are they open 24 hours, seven days a week? Is Penney's? Is Sears?)
Either the glass is half empty and you just kick back, relax and sip to the last drop, or the glass is half full and you roll up your sleeves and create ways to fill it.
What's the new potion in this magic XmR bottle that enables us to approach print production more sensibly, more logically? "How, Don Wheeler, do I listen to my process?" Well, first of all it's not a new potion at all. A statistician named Walter Shewhart developed it back in the 1920s and his student W. Edwards Deming taught it to the Japanese to enable them to compete with us—without cost accounting, by the way.
We didn't have hand-held calculators and computers at the time, so Shewhart devised some simple shortcuts for calculating "control limits"—the "range" of expected variation. It's an application of "Central Limit Theorem" modified by Shewhart, preached by Deming and refined by Wheeler to use "Moving Ranges" of data.
These moving ranges, with their process limits, enable us to know whether we're still just feeling the butterfly wings of print chaos or whether some attributable cause has intervened. XmR charts teach us to expect and accept variation within limits. Still want to markup costs for a price to quote? XmR will tell you the best, worst and most likely result to expect. Want to use a D-B-R (Drum-Buffer-Rope) scheduling system? Then set your buffers and feed rope based on "What your process is telling you," not your dreams. Want to have on "on-time" delivery monitoring?