
Statistical process control after W. Edwards Deming - Tomte
https://www.2uo.de/deming/
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pps43
> there isn't a hard theorem why they should sit at +/-3σ

There is Vysochanskij-Petunin inequality [1]. 95% of observations should fall
within +/-3σ away from the mean, assuming unimodal distribution and finite
variance.

[1]
[https://en.wikipedia.org/wiki/Vysochanskij%E2%80%93Petunin_i...](https://en.wikipedia.org/wiki/Vysochanskij%E2%80%93Petunin_inequality)

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conformist
Thanks, I wasn't aware of this and it seems very useful! Good to know a
tighter bound than Chabyshev's inequality (assuming unimodality).

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oso2k
It's also where Six Sigma (3 sigma on each side) comes from. It implies "Total
Control".

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curiouscats
Online resources on applying Deming's ideas [https://blog.deming.org/online-
deming-resources/](https://blog.deming.org/online-deming-resources/)

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conformist
If I remember correctly, Deming was a key inspiration for Charles Koch's (of
Koch industry fame/notoriety) managerial strategy.

See also
[https://en.m.wikipedia.org/wiki/The_Science_of_Success](https://en.m.wikipedia.org/wiki/The_Science_of_Success)

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hbarka
Philip B. Crosby and Joseph M. Duran

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kristianp
It's actually Joseph M. Juran, sounds the same if you're listening to an
audiobook.

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hbarka
Yes, you’re absolutely right. Iphone spellcheck likes Duranduran. My
department worshipped Juran when we were manufacturing things.

