Abstract
Group testing, the simultaneous testing of more than one unit be one test, can provide a substanial economy. The procedure of simultaneous testing is described i two situations : (1) When retesting of conforming units in groups is necessary. (2) When no retesting is required. In this paper, a concept of group fraction defective is newly introduced and group testing situations with retest and without retest are respectively investigated from the economic viewpoints. Concretely, the procedure for deciding the group size of the group testing without retest is presented which minimizes the expected cost instead of the expected numver of tests needed. The preliminary testing for deciding the adoption of group testing is also considered from the economic veiwpoints based on prior information about the lot quality.
