A note on acceptance sampling for variables

For 60 years acceptance sampling by variables has been recommended as an economic alternative to attribute sampling. Entry in the industrial practice happened after these plans were adopted in 1957 as Military Standard 414 by the US Army. Nowadays a slightly modified version of Mil-Std-414 is known as ANSI/ASQC Z1.9 or as International Standard ISO 3951. In this paper it is shown that the derivation of sampling plans by variables is based on assumptions which don’t hold, that acceptance sampling by variables is inappropriate, and that it doesn’t constitute an alternative to attribute sampling.