## ::Measurement

### ::concepts

Units::system    Which::metric    Value::systems    Units::length    Metre::united    Theory::quantum

{{ safesubst:#invoke:Unsubst||\$N=Use British English |date=__DATE__ |\$B= }} Measurement is the assignment of a number to a characteristic of an object or event, which can be compared with other objects or events.<ref name=pedhazur>{{#invoke:citation/CS1|citation |CitationClass=book }}</ref><ref name = bipm>{{#invoke:citation/CS1|citation |CitationClass=book }}</ref> The scope and application of a measurement is dependent on the context and discipline. In the natural sciences and engineering, measurements do not apply to nominal properties of objects or events, which is consistent with the guidelines of the International vocabulary of metrology published by the International Bureau of Weights and Measures.<ref name=bipm /> However, in other fields such as statistics as well as the social and behavioral sciences, measurements can have multiple levels, which would include nominal, ordinal, interval, and ratio scales.<ref name=pedhazur /><ref name = "Koch 2008"></ref>

Measurement is a cornerstone of trade, science, technology, and quantitative research in many disciplines. Historically, many measurement systems existed for the varied fields of human existence to facilitate comparisons in these fields. Often these were achieved by local agreements between trading partners or collaborators. Since the 18th century, developments progressed towards unifying, widely accepted standards that resulted in the modern International System of Units (SI). This system reduces all physical measurements to a mathematical combination of seven base units. The science of measurement is pursued in the field of metrology.

A typical tape measure with both metric and US units and two US pennies for comparison

Measurement sections
Intro  Methodology  Standardization of measurement units  Units and systems  Difficulties  Definitions and theories  See also  References  External links

 PREVIOUS: Intro NEXT: Methodology << >>