Studies of the reliability of constituent target values established in a large inter-laboratory survey

Lyophilized serum specimens were manufactured in such a way that fixed quantitative interspecimen relationships were established. The specimens were analyzed for about twenty constituents by several thousand laboratories in 1971, 1972, and 1973. Most of the consensus mean values derived from these analyses were found to relect accurately the relationships established in the manufacture of the specimens. In addition, analyses of some of the specimens for calcium by the National Bureau of Standards confirmed the relationships. I conclude that the consensus mean values derived for most constituents are reproducible and any biases that may be present are consistent from survey to survey.