Tolerance
A numeric range that defines how much a quality measure may deviate from its target and still meet requirements.
Key Points
- Expressed as measurable limits (for example, +/- values or a range).
- Sets the acceptable spread around a specified quality target.
- Established by stakeholders, standards, or contracts to guide acceptance decisions.
- Different from control limits, which relate to process performance monitoring.
Example
A component must be 100 mm in length with a tolerance of +/- 2 mm. Any part between 98 mm and 102 mm meets the quality requirement; outside this range it is rejected or reworked.
PMP Example Question
Which term describes the predefined numeric range that specifies how far a quality characteristic can vary from its target and still be acceptable?
- Tolerance
- Control limit
- Threshold
- Key performance indicator (KPI)
Correct Answer: A — Tolerance
Explanation: Tolerance defines the allowable variation around a quality specification; control limits relate to process control charts, thresholds trigger actions, and KPIs are measures of performance.