Does your measurement pass or fail?

All measurements come with some uncertainty. When your measurement plus the uncertainty fall within test limits, you can be highly confident that your product meets specifications. But what happens when the measurement is right at the test limit and the added uncertainty causes some possible values to exceed the test limit? The product could be out of tolerance, but you can't be sure.

A measurement uncertainty can produce incorrect decisions when a measurement is near the test limit.

False passes could result in a product failing in the field, which could lead to dissatisfied customers and costly repairs or recalls. False failures result in good products that don't ship. You incur higher test costs because the "failed" units require additional testing to determine if they really failed.

Measurements whose uncertainties exceed a test limit indicate that either your measurement equipment needs calibration or your manufacturing process needs adjustment. To learn more about how to identify false passes and failures, you can read a paper called "Putting measurement uncertainty to work for you," by Todd Wendle, product marketing manager for the Support Business Unit at Agilent Technologies. Download the paper from www.tmworld.com/wendle.