What exactly is measurement?
When we conduct a process of measuring a particular quantity, the thing we are doing is comparing the unknown quantity (the magnitude of which we intend to identify) with that of a standard that has been predefined. Once they have been compared the ensuing result is identified with a numerical value. Measurement alone is the process by which the physical properties of objects can be identified in terms of numerical values.
An object will have various properties, and during the measuring process any one particular physical property of the object that needs to be measured is compared with a ‘standard unit’ that has been accepted by the industry as a measurement standard for that particular property. A numerical value for the property being measured can be arrived at by comparing how many times the ‘standard unit’ takes to cover the entire of the quantity under measurement.
For example, if the length of a car’s body is to be measured, and if the standard unit is ‘millimeter’, then the car is measured to see how many units of ‘millimeter’ makes up the length of the car. Thus, the length property of the car is compared with an accepted standard unit like the ‘millimeter’, and is expressed by a numerical value after the comparison is complete.
The image shows the dimensions of a popular brand of car. The dimensions have been calculated in millimeters.
In measurements it is important that the numerical value of measurement is always followed by the unit, else the measurement will have no meaning. It is the unit that identifies the property of the object that is being measured. Thus, in the above example the unit is millimeter and indicates that it was the property ‘length’ that was measured. Likewise, there is a unit for area, volume, and so forth.
Thus, while making measurement the things that cannot be ignored and which brings meaning to the measurements made are that the ‘standard’ used for the comparison purposes is an industry accepted one and that it has been properly defined. Further, the device used to make the measurement and the method used to make the measurement should be provable.