Definition

A measure of the extent to which the measurements reported by a sensor can explain the concentrations reported by the reference instrument. It is often quantified by the coefficient of determination (R2) obtained from the simple linear regression fitting sensor measurements (y-axis) to reference instrument measurements (x­axis) with values closer to 1 generally indicating better linearity. In some cases, sensor measurements can be linear with a near perfect R2 but may differ significantly from the reference instrument measurements. For example, a linear regression can result in an R2 of 0.99 and slope of 5. This indicates that the reported sensor measurement is always 5 times higher than the reference instrument measurements.