Intro to Measurement System Analysis

Measurement System Analysis

Measurements are used to guide decisions, more error in the measurements, more error in the decisions based on those.

•        Purpose of Measurement System Analysis is to

–       Qualify a measurement system for use

–       Quantifying its accuracy, precision, and stability

•        Factors that are affecting measurement system includes

–       Equipment – Measuring instrument, fixtures etc.,

–       People – Operators, training, skill etc.,

–       Process – Method, specification

–       Samples – Sampling plan, sample selection

–       Environment – temperature, humidity

Variation in the process can be of two reasons

·        True Process Variation

·        Variation Due To Measurement

o   Bias - Difference between average of measurements and an agreed upon standard

§  Accuracy - Closeness between the average value to its actual value

§  Linearity - Difference in accuracy across expected range of measurement system

§  Stability - consistency of measurement system over a period of time

o   Precision - Variation in the measures when the same part is measured repeatedly

§  Repeatability - Measures the inherent variation in the instrument

§  Reproducibility – Measures the variation due to measurement system