mesure

Mesure is the act of determining the magnitude of a property by comparing it with a reference standard. In science and industry, measurements assign numerical values to quantities such as length, mass, time, temperature, and electric current. The term is common in French and other languages; in English the closest equivalent is measurement.

Metrology is the science of measurement. It covers theory, methods, and standards used to ensure reliability. Central to metrology are internationally agreed units, particularly the International System of Units (SI). Measurements are considered traceable when their values can be linked to SI units through a documented calibration chain.

An individual measurement has accuracy, precision, and uncertainty. Accuracy describes closeness to the true value; precision refers to reproducibility. Uncertainty expresses the doubt about the result and depends on instrument, method, and conditions. Calibration, error analysis, and quality controls help manage these aspects.

Methods and instruments vary by quantity. Direct measurement uses a device to read the quantity; indirect measurement relies on related quantities or calculations. Instruments include rulers, balances, thermometers, and voltmeters. Proper calibration and maintenance are essential to ensure trustworthy results.

Measurement scales range from nominal and ordinal to interval and ratio, with ratio scales incorporating a true zero. Units can be base SI units or derived units. In practice, measurement also encompasses estimation, sampling, and uncertainty evaluation in complex systems.

History features standardization and the metric system, culminating in SI adoption in the 20th century. Today measurement underpins science, technology, commerce, and daily life, from laboratory experiments to manufacturing tolerances and environmental monitoring.