TECHNOLOGY OVERVIEW

Gauge Bias Linearity (multiple equipment)

BIS.Net Team

Bias in the measurement system is the difference between the average of measured values and the actual value of a part. The actual value of the part is called the reference value. Ideally the bias should be zero.

The above image shows the variation in the different measurements on the same part about the average and the deviation of the average from the reference value. In this instance the bias is negative.

A multiple equipment study is an extension of a single linearity study performed by one appraiser using one equipment. It is not uncommon for multiple measuring devices to be available for testing the same parts. Due to faulty equipment, it cannot be assumed that each measuring device has the same linearity. To establish differences, or consistency, or absence of linearity amongst all measuring devices a multiple equipment linearity analysis must be carried out.

BIS.Net Analyst provides this information through an Analysis of Covariance which includes the Analysis of Covariance, Scatter Chart, Slope Consistency Chart and Probability Ploy. The slope consistency chart is a powerful visualization tool that can be used to confirm the Analysis of Covariance and visualize differences in linearity and overall linearity