[AT] Statistics In Tractor Manufacturing Was Bicycle Program

[Stephen Offiler]

I used to use Weibull statistics rather often, but that was 25 years ago
and I'm pretty rusty now.  That company manufactured (among other things)
various automotive sensors and aircraft circuit breakers.  We did a lot of
"Life Testing" to the point that we had a whole department with the same
name.  My recollection of Weibull statistics was that we'd record failures
(either time to failure or cycles to failure) and plot on a special chart
paper that had logarithmic axes.  Near the end, somebody figured out how to
do it with a spreadsheet but it was Lotus 1-2-3, not Excel (yet).  The
Weibull method had some significant benefits; for one, you only needed a
handful of data point to get meaningful results; for another, the way the
failure points arranged themselves on that chart paper would tell you
whether you were dealing with a single failure mode or mixed modes.

SO


On Sat, Sep 14, 2019 at 11:27 AM James Peck <jamesgpeck at hotmail.com> wrote:

> Some years ago I did participate in an academic Statistical Quality
> Control course. Much of the course involved the Weibull Distribution. If I
> remember correctly, the Weibull Curve predicted the lifespan of a
> manufactured assembly such as a tractor.  It appears to be a gift from the
> mathematicians.
>
> https://en.wikipedia.org/wiki/Weibull_distribution
>
> The same distribution probably predicts that Cecil’s New Holland money pit
> will continue to be so and will suffer an early demise.
>
> [Stephen Offiler] I never took a whole semester of Statistics.  Instead,
> we had a course called Engineering Experimentation, which was heavy on
> experiment design and statistical data analysis.  That gave me a very good
> appreciation for the practical application of statistics.   Out in the real
> world, on-the-job training programs in quality control principles in
> manufacturing (Deming, Juran, Lean Six Sigma) continued to solidify the
> practical applications.
>
> [Cecil Bearden] Steve: I nearly flunked statistics I only passed because I
> was a graduating senior.  However, I did flunk Rocks & Clods 2124 and had
> to find another 4 hours to graduate.   Then 35 years later I retire as a
> Geotechnical engineer designing foundations. !!!
>
> [Stephen Offiler] I'm not sure if that is an interesting statistic, or
> simply predictable statistically.  All you just said is that a bell-curve
> distribution for 2-year degrees overlaps a bell-curve distribution for
> 4-year degrees.
>
> [ James Peck] The interesting statistic is that some technical 2 year
> programs have higher starting incomes than many 4 year degree programs.
> People who complete such a program can later take a 2+2 program to get a
> four year degree if they choose.
>
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