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GaugeRepeatabilityEvents¤

Measurement System Analysis (MSA) for inline sensors. Evaluates repeatability and reproducibility using repeated measurements.

Module: ts_shape.events.quality.gauge_repeatability
Guide: Quality Control & SPC

When to Use¤

Use for Measurement System Analysis when qualifying inline sensors. Required by IATF 16949 and other quality standards. Evaluates whether measurement variation comes from the equipment (repeatability) or the operator/condition (reproducibility). Run during sensor installation, after calibration, or on a periodic qualification schedule.

Quick Example¤

from ts_shape.events.quality.gauge_repeatability import GaugeRepeatabilityEvents

grr = GaugeRepeatabilityEvents(
    df,
    value_column="measurement",
    part_column="part_id",
    operator_column="operator",
)

# Equipment Variation (repeatability)
ev = grr.repeatability(n_trials=3)

# Appraiser Variation (reproducibility)
av = grr.reproducibility()

# Full GR&R summary with tolerance range
summary = grr.gauge_rr_summary(tolerance_range=10.0)
print(f"GR&R %: {summary['grr_percent']:.1f}%")
print(f"Acceptable: {summary['grr_percent'] < 10}")

Key Methods¤

Method Purpose Returns
repeatability(n_trials=None) Equipment Variation (EV) — within-operator, within-part variation Dictionary with EV metrics
reproducibility() Appraiser Variation (AV) — between-operator variation Dictionary with AV metrics
gauge_rr_summary(tolerance_range=None) Full GR&R summary: EV, AV, GR&R, %GR&R, ndc Dictionary with complete MSA results
measurement_bias(reference_values) Compare measurements to known reference standards DataFrame with bias statistics

Tips & Notes¤

Interpret %GR&R against AIAG guidelines

A %GR&R below 10% is generally acceptable, 10-30% may be acceptable depending on the application, and above 30% indicates the measurement system needs improvement. Always provide the tolerance_range to get %GR&R relative to the specification width.

Related modules

See Also¤