CONTINUOUS SAMPLING PROCEDURES WITHOUT CONTROL

1. Summary. Several modifications of the Dodge CSP-1 procedure [1] are presented. Changes are made in the rule of action when a defective item is observed while on sampling. The Average Outgoing Quality Limit (AOQL) for these new procedures are derived without the assumption of control. These results are compared with the AOQL assuming control. A production process is said to be in statistical control if there is a constant probability p that an item is defective, and if the states of all the items (defective or nondefective) are stochastically independent. Further, the AOQL for the CSP-1 procedure using probability sampling (looking at every item with probability l/k when on sampling) is derived without the assumption of control. 2. Introduction and results. Two continuous sampling procedures are considered. The first procedure is denoted by CSP-42 and is as follows: a) At the outset, inspect 100 per cent of the units consecutively as produced and continue such inspection until i units in succession are found clear of defects. b) When i units in succession are found clear of defects, discontinue 100 per cent inspection, and inspect only a fraction l/k of the units, choosing the item to be observed at random from a segment of size k (this type of sampling will be called random sampling). c) If a sample unit is found defective revert immediately to 100 per cent inspection, eliminating from the production process the remaining (k - 1) items in the segment, and commencing 100 per cent inspection with the next item fol