Kipp&Zonen BSRN Scientific Solar Monitoring System - Manual (Page 172)

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Notes:
a.
The value of a quantity m ay be positive, negative or zero.
b. The value of a quantity m ay be expressed in m ore than one way.
c. The values of quantities of dim ension one are generally expressed as pure num bers.
d. A quantity that cannot be expressed as a unit of m easurem ent m ultiplied by a num ber m ay be
expressed by reference to a conventional reference scale or to a m easurem ent procedure or to
both.
True value (of a quantity)
Value consistent with the definition of a given particular quantity.
Notes:
a.
This is a value that would be obtained by a perfect m easurem ent.
b. True values are by nature indeterm inate.
c. The indefinite article “a,” rather than the definite article “the,” is used in conjunction with “true value”
because there m ay be m any values consistent with the definition of a given particular quantity.
Conventional true value (of a quantity)
Value attributed to a particular quantity and accepted, som etim es by convention, as having an uncertainty
appropriate for a given purpose.
Notes:
a.
“Conventional true value” is som etim es called assigned value, best estim ate of the value, conventional
value or reference value.
b. Frequently, a num ber of results of m easurem ents of a quantity are used to establish a conventional
true value.
Measurement
Set of operations having the object of determ ining a value of a quantity.
Note:
a.
The operations m ay be perform ed autom atically.
Principle of measurement
Scientific basis of m easurem ent
Method of measurement
Logical sequence of operations, described generically, used in the perform ance of m easurem ents.
Note:
a.
Methods of m easurem ent m ay be qualified in various ways such as:
i.
Substitution m ethod
ii. Differential m ethod
iii. Null m ethod
Measurement procedure
Set of operations that are described specifically and are used in the perform ance of particular
m easurem ents according to a given m ethod.
Note:
a.
A m easurem ent procedure is usually recorded in a docum ent that is som etim es itself called a
“m easurem ent procedure” (or a m easurem ent m ethod) and is usually in sufficient detail to enable
an operator to carry out a m easurem ent without additional inform ation.
Measurand
Particular quantity subject to m easurem ent
Note:
a.
The specification of a m easurand m ay require statem ents about quantities such as tim e, tem perature
and pressure.