Design and operation of an expanded system of quality control.

‘THE VALUE of a pooled serum and a quality control chart in monitoring clinical chemical analyses is well-established (1, 2). However, any of the following situations may arise in a laboratory which relies solely on such a system of quality control: (1) a test may give reliable results in the normal, but unreliable in the high or low ranges; (2) poor technician performance may be masked by bias in analysis of pooled serum specimens; and (3) frequent clerical, labeling, and calculating errors may render results unreliable despite the use of precise and accurate chemical methods. Various remedies for these inadequacies, such as using blind checks, using control materials giving abnormally high or low results, participating in national surveys, or having specimens analyzed by reference laboratories, have been suggested. The quality control program to be described, which has been in routine operation since April 1966, represents our efforts to overcome the deficiencies of the pooled serum program in a systematized manner. The daily output of data is computerized to maintain a running mean (i), standard deviation (S.D.), and coefficient of variation (C.V.) for each test and for each technician. Specific objectives of the program: (1) provide a measurement of technician skill and objectivity, (2)