Principles of Calibration
The concept of calibration is very broad. As a noun, the word means a set of graduations marked to indicate values such as the markings on a thermometer. Standardization is a term related to calibration. As used by chemists, it refers to the establishment of the value of a potential chemical standard, usually by comparison with a standard of known composition. The only purpose of calibration is to eliminate or minimize bias in a measurement process. The precisions of calibrated and uncalibrated systems can be equivalent. The prime requirement for calibration is the availability and use of appropriate and accurate standards. Minimally, they should have a high degree of similarity, and ideally, they should be identical to the object compared. Correlation coefficients are sometimes recommended for judgement of fit of an equation to a data set. While correlation coefficients are good tests for correlation, they are not necessarily good tests for linearity.