B

bias

Bias measures how far an observed value is from a target value and is expressed as a percentage. Bias is determined by a reference value or estimated from an outside source such as proficiency testing results or the Bio-Rad Unity™ Interlaboratory Program. Use the following formula to calculate bias:

Note: Bias is the total systematic error as contrasted to random error. There may be one or more systematic error components contributing to the bias. A larger systematic difference from the accepted reference value is reflected by a larger bias value. [ISO 3534-I]

Bias and Imprecision Histogram Report

The Bias and Imprecision Histogram Report is one of the Unity™ Interlaboratory Reports. This report provides a graphic representation of a laboratory's bias compared to the current cumulative consensus group mean and a laboratory's CV. On the chart, the monthly CV is represented as a bar and the bias is represented as a diamond with lines connecting each diamond. The Bias and Imprecision Histogram Report helps to detect changes in performance over time and to identify if the change in performance is due to imprecision, bias, or both.

Note: The Bias and Imprecision Histogram Report does not contain specific thresholds for allowable bias or allowable imprecision.