What is a measurement system analysis?

It is easier to answer this question using a practical example.

Let’s say you were taking the tire pressure of one of the tires on your truck every 5 minutes for 60 minutes. Each time you measured the pressure (on the same tire), you received a different psi. Since your tire pressure is changing so much, you have decided to purchase a new tire or better yet buy a whole new truck. Wouldn’t you like to know if this is truly a problem before you spend money on a new tire or a new truck? Is your tire pressure really changing each time you take the pressure?

A measurement system analysis can help you determine if your tire pressure is really changing each time you take a measurement or if the variability is due to your measurement system. A measurement system analysis is used to determine how much of your variability is due to the product or process versus the measurement system.

The tests for a measurement system analysis involve using multiple people and multiple pieces of equipment. In the case of measuring the tire pressure, you would use multiple different tire gauges and various individuals measuring the tire pressure.

Here are some key characteristics that are evaluated during a measurement system analysis (others exists):

Accuracy: The degree in which a measured value is close to the standard value.

Precision:

• Repeatability: The ability for the same person to get the same measurement on the same item after multiple attempts.
• Reproducibility: The ability for a different person (or people) to get the same measurement on the same item.

Stability: The ability for the measurement system to produce a consistent measure over time.

Linearity: The ability to determine if bias exists in the operating range of a measurement system.