MSA (Measurement System Analysis)

Statistical study conducted in Six Sigma Measure phase to assess whether measurement tools and methods are adequate for their intended use. Evaluates bias, linearity, stability, repeatability (same operator, multiple measurements), and reproducibility (different operators). Common method is Gage R&R study. If measurement variation exceeds 10% of process variation, the measurement system needs improvement before data can be trusted. Critical principle: if you can't measure it reliably, you can't improve it. Must be completed before baseline data collection.