COLLABORATIVE STUDY OF ESTIMATES BY RADIOIMMUNOASSAY OF INSULIN CONCENTRATIONS IN PLASMA SAMPLES EXAMINED IN GROUPS OF FIVE OR SIX LABORATORIES

in Journal of Endocrinology
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SUMMARY

Results of a collaborative study in which the insulin concentrations of a number of plasma samples were estimated in several laboratories are reported. They indicate that: (1) laboratories agreed on the ranking of plasma samples according to insulin content; (2) the reproducibility of replicate estimates obtained in the same assay usually overestimated the reproducibility of estimates made on different occasions; (3) values reported for the insulin concentration of the same plasma examined in each of a number of laboratories were likely to range from about one half to twice the inter-laboratory mean estimate.

Possible reasons for the variability of estimates are discussed.