ES438 Quality systems notes – Lecture 10 (Management)
The Concept of Natural Limits
Process outcomes will naturally vary
With sufficient data natural limits for the process under normal
circumstances can be defined.
The limits will only be exceeded when something special happens
, 2nd Principle of Understanding Data
“Every data set contains noise, some data sets contain signals”
Before you can detect a signal you need to filter out the noise
Control charts are used to filter out the noise
First Time Pass Rate Data
The difference between September and August is not significant
It is inappropriate to respond as if it were
How should we respond?
The Concept of Natural Limits
Process outcomes will naturally vary
With sufficient data natural limits for the process under normal
circumstances can be defined.
The limits will only be exceeded when something special happens
, 2nd Principle of Understanding Data
“Every data set contains noise, some data sets contain signals”
Before you can detect a signal you need to filter out the noise
Control charts are used to filter out the noise
First Time Pass Rate Data
The difference between September and August is not significant
It is inappropriate to respond as if it were
How should we respond?
