The study of the extent to which systematic and random factors are affecting our ability to correctly measure some phenomenon

Observed Result = true unknown value error .

Why is MSA important?

  • Incorrect decisions.
  • Greater sample sizes required.
  • Understates capability indices.
  • A bad one might be measured as good.
  • A good one might be measured as bad.

When is MSA implemented?

  • Before any data collection.
  • Prior to a process capability study.
  • Key characteristic or process is not capable.
  • Measurement system is suspected of being a significant source of variation.
  • There are major changes to the measurement system.
  • Before conducting an improvement study.
  • Criterion to accept new measuring equipment.

Elements of Measuring System

  • Standard.
  • Work piece (Part).
  • Instrument.
  • Person/Procedure.
  • Environment .