Calibration: What is it?
Calibration and adjustment are two separate things.
This document will establish a clear message about calibration: what it is, and, what it is not. It will prove that calibration and adjustment are not the same thing. While the concept of calibration applies to all measurement devices, this paper focuses on weighing devices.
You calibrate a weighing device to understand how it behaves. You adjust the device to change its behavior. It makes sense that you would not want to change the behavior of a weighing device until you first understand how it behaves. If the device does not behave well enough, then you adjust something to change its behavior. The process to understand how the weighing instrument behaves is the calibration. Therefore, it is reasonable and common to calibrate a weighing device without adjusting it.
Adjustment is not calibration. You can calibrate a measurement device without adjusting it. Calibration is developing an understanding of a measurement device. Calibration should include the determination of the measurement uncertainty to enhance the understanding of the measuring device.
The International Bureau of Weights and Measures (BIPM) states the following about calibration:
"Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication."