In SPC and Control Charts, which scale is used?

In SPC and Control Charts, which scale is used?

• A. 6 Sigma
• B. Gantt Chart
• C. Pareto
• D. ISO 9001

Answer: (A)

In SPC and control charts, the scale used is the sigma scale—data are measured in units of standard deviation from the process mean. This lets you set control limits at about plus or minus three sigma and evaluate how far the process is from its target. This same sigma-based view underpins Six Sigma, which describes process performance in sigma units (higher sigma means fewer defects). The other options aren’t scales used in SPC: a Gantt chart for scheduling, a Pareto chart for prioritizing defects, and ISO 9001 is a quality management standard rather than a measurement scale.

In SPC and control charts, the scale used is the sigma scale—data are measured in units of standard deviation from the process mean. This lets you set control limits at about plus or minus three sigma and evaluate how far the process is from its target. This same sigma-based view underpins Six Sigma, which describes process performance in sigma units (higher sigma means fewer defects). The other options aren’t scales used in SPC: a Gantt chart for scheduling, a Pareto chart for prioritizing defects, and ISO 9001 is a quality management standard rather than a measurement scale.