IUPAC - performance score (08095)

performance score

synonym: performance statistic

https://doi.org/10.1351/goldbook.08095

Statistic, derived from a result reported by a participant in a proficiency testing scheme, used in interpretation of participant performance and to allow comparison with defined objectives.

Notes:

The purpose of a performance score is to express the deviation of the reported value from the assigned value in a proficiency testing scheme in a manner that allows comparison with performance criteria.
Names and defining equations of frequently used performance scores are listed in Table 1. Their definitions and interpretations are given in ISO/IEC 17043 and ISO 13528.

**Table 1** Examples of performance scores used in *proficiency testing.*
Name	Symbol	Defining equation	Equation symbols
z score	z	$z_{i} = \frac{x_{i} - x_{P T}}{σ_{P T}}$	x_i: i^th reported value, x_PT: assigned value. σ_PT: standard deviation for proficiency assessment.
z’ score z prime score	z’	$z_{i}^{'} = \frac{x_{i} - x_{P T}}{\sqrt{σ_{P T}^{2} + u^{2} (x_{P T})}}$	u(x_PT): standard measurement uncertainty of the assigned value.
ζ score zeta score	ζ	$ζ_{i} = \frac{x_{i} - x_{P T}}{\sqrt{u^{2} (x_{i}) + u^{2} (x_{P T})}}$	u(x_i): standard measurement uncertainty of the reported value.
E_n score E_n number	E_n	$E_{n} (i) = \frac{x_{i} - x_{P T}}{\sqrt{U^{2} (x_{i}) + U^{2} (x_{P T})}}$	U(x_PT): expanded measurement uncertainty of the assigned value. (Usually with a coverage probability of approximately 95 %). U(x_i): expanded measurement uncertainty of the participant’s result. (Usually with a coverage probability of approximately 95 %).

Source:
PAC, 2021, 93, 997. (Metrological and quality concepts in analytical chemistry (IUPAC Recommendations 2021)) on page 1031 [Terms] [Paper]

Citation: 'performance score' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.08095 RIS BibTex EndNote

Div. V Text XML JSON

Alphabetical Index

Additional Indexes

Version 3.0.1 (8063 Terms)

performance score