The Importance of a Blind Control in the Establishment of Assigned Values in Control Sera. The Establishment of Assigned Values in Control Sera, I.

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Abstract
A study is described by which the establishment of assigned values of a control serum was stimulated. The study covered 2 controls: the internal known control and a blind control. Seven constituents [creatinine, glucose, urea, alanine aminotransferase (EC 2.6.1.2), aspartate aminotransferase (EC 2.6.1.1), creatine kinase (EC 2.7.3.2), .gamma.-glutamyltransferase (EC 2.3.2.2)] were analyzed in 10 or 11 laboratories, respectively, yielding a total of 72 sets of analytical values. Each set covered double determinations within .apprx. 18 series for each sample. The course of a blind control correlates better with the unknown sample for which assigned values are to be determined than does a known control. Of 72 sets, 5 sets were found incorrect. Of these, 2 sets could be recognized exclusively by means of the blind control and 2 others primarily by means of the known control; one of these could be detected by means of the double determinations. Consequently, a blind control has a greater control efficiency than double determinations.