Off to the Milky Way

Use moving ranges to redirect a vague meeting about a vague problem

I received the following note from a physician who is very interested in improvement: “I am not sure I understand what a process behavior chart and a moving range chart do to the discussion, and what do the colored lines represent? aka ‘Still confused.’”

His comment was in response to my column, “What Are You Tolerating?”, which included the two graphs in figure 1. I’d like to take a step back and address his question in the hopes of helping him (and you) avoid yet another vague meeting about a vague problem with some vague data. “Off to the Milky Way,” incidentally, was one of W. Edwards Deming’s favorite expressions and describes that scenario very well.

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moving ... first of all

After many years of often insignificant average & range charts, in a recent Stastics refreshing training course, a Statistician brought again to light the moving range approach that I learned at school, in the late 60's. May be in those years production batches were as small as they have become since year 2008, or so. It may also be that ststisticians and their associate software makers have been milking industry for decades, and they now have to turn back to earn a meal out of their job. Isn't it odd that people charting everything don't chart their own processes? Thank you.

Thank you!

As always, Umberto, a heartfelt comment. The data plotted here are hardly "production batches," but, in service industries, a run chart/Individuals chart is THE bread-and-butter tool and extremely powerful as an initial analysis.

I have an MS in statistics, yet am seen as "pariah" amongst my peers -- they just keep developing "better jackhammers to drive tacks." At a conference a couple of weeks ago, someone mentioned how they had been mentored by a (relatively well-known) applied statistician; but my approach was much simpler, EVERY bit as effective, and much more intuitively understandable for people who aren't (and who don't want to be) statisticians.

Historical note: There were many internal statistical consulting groups in the '50-'70s who were allowed to act as (relatively high-salaried) "corporate eggheads" because they would run an occasional design that would salvage a major disaster. A LOT of good research came out of these groups. In the early '90s, I predicted that most of these groups would be analyzed as a business and be disbanded in 10 years...and have been proven right.

The easy availability of computers, software packages, and color printers -- coupled with statisticians' recalcitrance -- has rendered the formally degreed statistics profession moribund (except for pure research). In 1984, I saw a handwritten note from Deming to a very famous applied statistician at GE who shared some work with him in quality and productivity, "Sorry about your misunderstanding -- TOTAL! When will statisticians wake up?" From what I see, most of them are still sleeping...

Kind regards to my paesano,

Davis