In Canada, acceptance sampling has been used in legal metrology
applications for nearly four decades. One of its principal uses has been
in the quality control of utility meters that measure electricity or
natural gas supplied to consumers. By law, such meters must be inspected
for conformance to specification requirements prior to use and be
periodically inspected while huse. With few exceptions, due to the
numerous utility companies in the country and their varied practices,
the meters exist in the form of isolated lots for inspection purposes.
The proportion of nonconforming meters in a lot has traditionally
defined lot quality for utility meter sampling inspection purposes.
Another principal application of acceptance sampling has been in the
quality control of the net contents of packaged products sold in the
marketplace. Such products include those sold on the basis of such
measures as weight, volume, length, and area. In this particular
application, products are also usually inspected on an isolated-lot
basis for regulatory purposes. However, lot quality is usually measured
on the basis of two criteria for such products: the proportion of nonc-
forming packages in the lot and the lot mean quantity. This section
reviews Canadian quality control practices in these two areas of
application, highlighting some of the deficiencies and issues.
Three-class s- pling plans are proposed as a possible solution to some
of these deficiencies and issues.
