ABSTRACT
Calibration is the process of adjusting the setting of a tool according to a defined standard so that the readings provided by this tool have increased validity, i.e., they can be believed to be correct. This process is intimately related to quality control; it increases the confidence in the performance of the tool. A new tool must always be calibrated anyway, but an old tool also is calibrated when it is suspected to have “rusted” due to repeated use, misuse, or long nonuse. This clearly applies to laboratory and clinical instruments such as a biochemical analyzer and a sphygmomanometer. A questionnaire, say for assessing quality of life, also needs calibration when translated to another language so that it provides the same response as the original standard would in the identical setting.
