| Capability analysis: Indices |
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These indices show what the process is "capable" of doing. This is the six sigma
range of the inherent variation
of a statistically stable process
. Sigma is estimated using the
/d2 formula.
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These indices show what a process is actually doing. This is the six sigma range of the total process variation, where sigma is usually determined by the sample standard deviation
.
All of these capability indices can be calculated using software packages like CHARTrunner and SQCpack.
See also:
>> Can a process produce output within specifications?
>> Control vs capability
>> Normal data capability analysis
>> Non-normal data capability analysis
>> What is capability analysis and when is it used?
>> Learning more about capability