TABLE OF CONTENTS This Chapter deals with some more recent developments in the field of Process Capability when several characteristics of a process are involved. For completeness we shall present again some basic facts related to the subject matter under consideration, in our attempt to render this Chapter to be as self-contained as possible. Various quality measures have been proposed to evaluate a process's performance. In general, there are several issues to be considered when assessing product quality. First and foremost is the issue of process capability indices. A process capability index (PCI) is a numerical summary that compares the behavior of a product or processes characteristics related to engineering specifications. Its convenience is due to the reduction of complex information about the process to a single number. Specifically, process capability is universally defined as the range over which the measurements of a process vary when the process variation is due only to random causes. In this case, process capability indices do provide an effective measure of process capability. By using a process capability index, we may obtain a conclusion whether the product meets its specifications and is stable. Currently, numerous customers request their suppliers to record capability indices for product characteristics on a regular basis. In the majority of companies it became a key index to evaluate product quality. A large number of quality engineers and statisticians have proposed methodologies for assessing product/process quality. However, the bulk of the studies associated with analyzing the quality and efficiency of a process,...
