Measures and metrics are tools that help organizations recognize their successes, understand their challenges and improve performance. When used well, they can increase confidence in decisions and move discussions away from anecdotes and one person’s view of the problem.
A measure is a set of data that can be countably added together. The measure theory of a vector space is the mathematical discipline that studies these concepts.
Units of Measurement
There are a wide variety of units used to measure physical quantities. The most commonly used system is the International System of Units, or SI (abbreviated from the French term Système International d’unités). It has seven base units—the second (symbol s), meter (m, length), kilogram (kg, mass), ampere (A, electric current), kelvin (K, thermodynamic temperature) and mole (mol, amount of substance)—from which coherent derived units are defined as products or powers.
The SI bases its definitions on constants that describe the natural world. This separation of the defining constants from the definitions of units means that improved measurements can be made and new realisations of existing base units can be introduced without having to redefine them. This process is called a mises en pratique. It is important to understand how the metric system works and its conventions to use it effectively. This includes understanding the role of prefixes and how they systematically construct, for a given physical quantity, a set of decimal multiples that cover a broad range.
Measurement in Physics
Physicists use measurements to answer questions about the nature of physical phenomena. In order to make accurate measurements, physicists need to understand a variety of measurement units. These are standardized values that allow scientists to communicate and compare the results of experiments.
There are many different systems of measurement in the world, but most physics studies are done with measurements made by using a standard system called the International System of Units (SI) that is based on seven base units: meters for length, kilograms for mass, seconds for time, amperes for electric current, kelvins for temperature and moles for amount of substance. The other quantities we measure are derived from these base units by using mathematical operations.
All measurements have some uncertainty associated with them, which must be reflected in the final number. The precision of the measuring device used can affect the accuracy of the result. Other factors that can cause errors are environmental conditions, human error and systematic error.
Measurement in Chemistry
The field of Chemistry depends on precise and accurate measurements to understand and replicate chemical reactions. A standard framework, like the metric system that includes base units such as length (meter), mass (kilogram), time (second) and temperature (kelvin), enables chemists to collaborate internationally by allowing them to use the same measurement unit to describe and compare results.
In chemistry, measuring instruments such as balances for weight, graduated cylinders for volume and thermometers for temperature are common laboratory tools used to make measurements. Spectrometers and chromatography are other more advanced measurement techniques that enable chemists to work at atomic and sub-atomic scales.
As with all measurements, there is always room for uncertainty in the laboratory but the practice of best practices and following a set of rules can help to minimise error. Significant figures are important in indicating the accuracy of a number and there are specific rules about how many decimal places to include. This allows chemists to easily compare results from different publications without needing to calculate or convert.
Measurement in Technology
The ability to measure the dimensions, shape and properties of objects and materials is essential for a wide range of technologies. In manufacturing, engineering, the sciences and other fields, accurate and precise measurement is often crucial to statistical process control or other quality-control techniques.
Understanding the units of measurement is a critical component in technology education. In order to develop, build and maintain advanced technology systems, it is important that individuals understand how measurements work.
The field of measurement science is known as metrology, and it focuses on the development of more effective means of measuring objects and effects. A key aspect of metrology is that a measurement has the quality of traceability, meaning that it can be linked back to an international standard such as the SI – the International System of Units. This ensures that people get what they pay for and that the products they purchase are of good quality. It also helps to ensure that trade is fair and equitable.