# Gage R&R

**URL:** https://kaizumi.com/dictionary/gage-r-and-r

**Description:** Gage R&R (Repeatability and Reproducibility) is a study that quantifies measurement system variation to ensure data quality for process improvement.

**Category:** six-sigma

**Tags:** metrics, quality, foundational

## Definition

Gage R&R (Repeatability and Reproducibility) is a statistical study that quantifies how much observed variation comes from the measurement system versus the actual process. Repeatability measures variation when one operator measures the same item multiple times; reproducibility measures variation when different operators measure the same item. A capable measurement system should contribute less than 10% of total observed variation. Gage R&R is essential in the Measure phase of DMAIC—without good measurements, analysis and improvement efforts are built on unreliable data.

## Examples

### Manufacturing

> Before a Six Sigma project on dimensional variation, the team conducted a Gage R&R with 3 operators measuring 10 parts 3 times each. Results showed 35% of variation came from measurement—mostly reproducibility (different operators got different results). They standardized measurement technique before proceeding.

### Healthcare

> A laboratory assessed blood pressure measurement across nurses. Gage R&R revealed 25% measurement variation, primarily from reproducibility (different nurses, different readings). Training on cuff placement and timing reduced measurement contribution to 8%.

### Administrative

> A call center's quality scoring system showed high variation in scores. Gage R&R with 4 scorers rating 15 calls showed 45% variation from reproducibility—scorers interpreted criteria differently. Calibration sessions and clarified rubrics reduced this to 12%.

## Key Points

- Target: measurement system contributes <10% of total variation
- Repeatability = within-operator variation (same person, same item, multiple measurements)
- Reproducibility = between-operator variation (different people measuring same item)
- Conduct Gage R&R before using data for process analysis

## Common Misconceptions

**Good equipment means good measurements.** Measurement variation often comes from operators, methods, and environment—not equipment. Gage R&R separates these sources. Expensive equipment with inconsistent technique still yields poor data.

**Gage R&R is only for physical measurements.** Any assessment system benefits from Gage R&R—visual inspections, subjective ratings, software testing. If humans judge outcomes, reproducibility studies reveal inconsistency that undermines decisions.

## Related Tool

Once your element-time measurements pass Gage R&R, stack those validated times against takt time to balance the work across stations with the [free Yamazumi builder](/tools/yamazumi).

Source: https://kaizumi.com/dictionary/gage-r-and-r
Licence: free to quote and cite with attribution to Kaizumi.