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Measurement is the process of obtaining the magnitude of a quantity relative to an agreed standard. This science story focuses on the agreed standards of measurement in use in New Zealand.

Measurement of any quantity involves comparison with some precisely defined unit value of the quantity. Standard units of measure need to be identified and defined as accurately as possible.

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The system that is used in the scientific community is called Système International d’Unités, abbreviated to SI.

All of the SI units used in scientific measurements can be derived from just seven fundamental units. Apart from mass, each of these units has a definition based on an unchanging property of nature. Measurement scientists are working to find a suitable replacement for mass based on known physical constants.

A number of non-SI units are commonly used, even though the SI system of units covers all scientific measurements. The reasons for this are historical, political and for everyday convenience.

In order to properly use and apply the International System of Units (SI), a set of guidelines for expressing quantities using specific style conventions has been developed.