For the newcomer, unfamiliarity with the specialist vocabulary of scientific disciplines like physics and chemistry can act as an obstacle to learning those disciplines. What can be even more challenging is that science employs many words such as force and energy that are used in various ways in everyday language. The science of measurement, in particular, has many terms, such as error, uncertainty and accuracy, that also occur in day-to-day use in contexts far removed from measurement. In this chapter we consider terms used in measurement, including those with an everyday or popular meaning such as error, and we clarify their meaning when used in the context of measurement.

Measurement and related terms

Measurement

Measurement is a process by which a value of a particular quantity such as the temperature of a water bath or the pH of a solution is obtained. In the case of length measurement, this might involve measuring the atomic-scale topography of a surface using an instrument such as an atomic-force microscope (AFM), or measuring the length of a pendulum using a metre rule. Values obtained through measurement form the foundation upon which we are able to

• test both new and established scientific theories;

• decide whether a component, such as a resistor, is within specification;

• compare values obtained by workers around the world of a particular quantity, such as the thickness of the ozone layer of the atmosphere;

• quantify the amount of a particular chemical species, such as the amount of steroid in a sample of urine taken from an athlete; and

• establish the proficiency of laboratories involved with the testing and calibration of equipment.