Arbitrary number ratio - Dynamic NPU Manual

Arbitrary number ratio

Definition in words

Number ratio of component B in system 1 compared with number ratio of component B in a reference system

Note: The reference system is defined by the laboratory

Result type

Ordinal scale
  • Value set is ranked accoding to magnitude
  • The value set and the limit of the value set are defined by the laboratory
  • The value set can be either numerical values or words.

Example 1

Value set={none < some < high < very high}

Example 2

Value set={low < normal< high }

Example 3

Value set={0 < 1 < 2}

Example 4

Value set={negative < positive}

Example 5

Value set={+ < ++ < +++}

  • Algebraic operations are not allowed (Ref. 2, 1.26)
  • Possible comparison of values (a<b, a=b or a>b)



Special rule(s) in the NPU syntax

“Procedure” is stated in the specification to the kind-of-property in the NPU definition.

“Procedure” indicates that the measurement procedure must be stated somewhere else than the NPU code and there may be difficulties in comparing values for the same NPU code.


  1. Ferard G, Dybkaer R, Fuentes-Arderiu X. Compendium of Terminology and Nomenclature of Properties in Clinical Laboratory Sciences : Recommendations 2016. 1 ed: Royal Society of Chemistry; 2016. 182 p.
  2. Mesures BIdPe. International Vocabulary of Metrology – Basic and General Concepts and Associated Terms VIM 3rd edition JCGM 200:2012 (JCGM 200:2008 with minor corrections). Bureau International des Poids et Mesures; 2008.

Laboratory field


Allergology Generic abbreviated form NPU58743 B—Erythroblasts/Leukocytes; arbitrary number ratio(proc.) = ?
Full form with a result NPU58743 Blood—Erythroblasts/Leukocytes; arbitrary number ratio(procedure) = ?
Abbreviated form with a result NPU58743 B—Erythroblasts/Leukocytes; arbitrary number ratio(proc.) = ?
Written expression The arbitrary threshold concentration of Aggregation, thrombin-induced of thrombocytes in Mr. Smith’s blood is [low], compared with arbitrary threshold concentration of Aggregation, thrombin-induced of thrombocytes in a reference system. The measurement is performed according to procedure defined by the laboratory.

The reference system is defined by the laboratory.

“Low” is a value according to a value set defined by the laboratory.

Reference NPU database, and
  • Kind-of-property

    • Nominal kind-of-property

    • Kind-of-quantity

      • Ordinal kind-of-quantity

        • Arbitrary number ratio


  • Dybkaer R. Concept system on ‘quantity’: formation and terminology. Accredit Qual Assur. 2013;18(3):253-60.
  • Dybkaer R. ISO terminological analysis of the VIM3 concepts ‘quantity’ and ‘kind-of-quantity’. Metrologia. 2010;47(3):127-34.
Date Term Note
2019-04-11 Arbitrary number ratio Term established