Measurement Capability Assurance through Identification and Compensation of 'Hidden Error'

With the advent of technologies, the equipment manufacturers are offering precision multifunction calibrators, precision multi meters, High accuracy DC Resistance Bridge, precision LCR meters etc. at competitive prices. Accordingly most of the Electro technical calibration laboratories are increasingly acquiring such higher end calibrators/standards to add business value with enhanced measurement capability. The measurement capability of such laboratories range from sub ppm level to single digit ppm level. Though it is possible to achieve the enhanced measurement capability as per the claimed specification and the methods specified by the equipment manufacturer, it often raises doubt whether in reality and practice the best measurement capability is achieved without adopting good measurement practices. This paper details good measurement practices to be established and implemented by calibration laboratories as part of measurement capability assurance to demonstrate its competence and capability to calibrate at low ppm level using precision calibrators and standards. An attempt is also made to highlight the possible errors known as hidden errors which get observed into measurement results and in certain cases errors introduced could be more than the best measurement uncertainty claimed by the laboratories.