Statistical Process Control (SPC)
Use time-ordered process data to distinguish routine variation from unusual signals.
What this topic covers
Use time-ordered process data to distinguish routine variation from unusual signals.
Core testing ideas
Control charts monitor process behaviour over time.
Control limits describe statistical behaviour and are not the same as engineering specification limits.
Signals should trigger investigation of the process rather than automatic product rejection.
Measurement and method limits
SPC and capability metrics describe process behaviour, while engineering specifications describe product requirements.
Evidence and traceability
Nonconformance, corrective action, audits and supplier controls close the loop when results do not meet expectations.
Using the result
Quality metrics should be defined consistently so improvement is real rather than a reporting artifact.