RE: Probability theory and the role of the mind

["Farey Bob" <Bob.Farey@metronetrail.com>]

Probability theory and the role of the mind

Given that the vast majority of companies in the UK have no idea what
the theory of variation is, or what a control chart is, or what are the
pitfalls of comparing this month's figures with last month's, or with
target, or with the use of rolling averages "to damp down the noise and
reveal trends", I would have thought that understanding how to construct
the appropriate chart and then interpret it using the normal "rules"
takes us from say 2/10  to 9/10. Those people and Companies at the 9/10
zone now have to understand their processes, identify the problems /
improvement opportunities, find appropriate solutions and implement
them, using the control charts to monitor the effect of the changes.
Maybe some will adopt balanced scorecards and six sigma methodologies.
Worrying about probability theory should be a low priority, in my
opinion. I would rather be right 95% of the time when I interpret a
chart, so I can keep the rules simple. After all, it is persons who work
on the process that need to understand, develop and interpret the
charts, and then identify and implement improvements. I always tell /
teach people that control charts are empirical rather than based on
rigorous statistical theory. I say "they work great, so let's use them".

Bob Farey