Measurement performance goals: How they can be estimated and a view to managing them

Figures & data

Table I. Analytical goals specified by Belk and Sunderman 1946 [7] and outcome of a survey by the Swedish EQAS Equalis (www.equalis.se, available in English). US values in g/dL, SE values in SI units. Glucose in the 1946 study was most likely “reducing substance”.

	Belk and Sunderman [7]				Equalis EQA survey 2010
	Anal goals	Range %	Number	% satisfactory	Number	Mean	CV%
Haemoglobin	9.8	±3.0	51	33.3
Haemoglobin	15.1	±3.3	52	40.4	270	135	1.5
Glucose	60	±16.6	52	63.5	90	4.6	3.2
Glucose	375	±8.0	51	52.9
Albumin	4.6	±6.5	44	20.5	89	43.9	4.2
Calcium	6.6	±7.6	43	32.6	92	2.35	2.5
Calcium	12.6	±4.0	44	31.8

Figure 1. A) The bias of the measured quantity value of a Certified Reference Material (CRM) is adjusted to the assigned value giving B) the “best estimate” of the quantity value with an increased uncertainty. The “best estimate” of the quantity value coincides with the assigned value of the CRM after the correction. The best estimate will be within the coverage interval with a stated probability (p). From CLSI, with permission

Table II. Results of recalibrating Apolipoprotein A1 and B.

	Mean mg/L, before	Between lab CV % before	Mean mg/L, after	Between lab CV % after
Apo A1	1.6	6.4	1.6	2.2
Apo B	1.0	5.8	1.0	1.7

Belk WP, Sunderman FW. A survey of the accuracy of chemical analyses in clinical laboratories. Am J Clin Pathol 1947;17:853–61.

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