Two variables sampling procedures with severity adjustments are proposed. A comparative study of the variables sampling standards, MIL-STD-414, ANSI Z 1.9, ISO 3951, and BS 6002 is examined and a questionaire study is also performed on the use of sampling standards in manufacturing industries.
The proposed sampling procedures are ; sampling procedure 1 with normal and tightened inspection plans only and sampling procedure 2 with normal, tightened and reduced inspection plans with the switching rules matching to KS A 3109 attributes sampling plans. For the two sampling procedures, composite operating characteristic (OC), average sample number (ASN), average total inspection (ATI), and average outgoing quality (AOQ) are evaluated. Sampling procedure 1 has slightly poorer discriminating power than ANSI Z 1.9, but it has simplified switching rules. Sampling procedure 2 has more complex switching rules than those of ANSI Z 1.9, but is has better discriminating power than ANSI Z 1.9 and smaller average sample number(ASN) than sampling procedure 1.
