ABSTRACT
This chapter focuses on an aspect of quality control that lies at the heart of all control activities called process control. In particular, it looks at the causes of variation in a process and discusses the methods commonly used to explain those variations. Since deviations from standards are relatively easy to measure, quality control studies frequently use conformance of standards as the principle guiding tool for quality measurement. However, quality is not always related to a good or service; it can also apply to an organization and its performance, such as decrease in crime rates for a community or increase in graduation rates for a school district. Perhaps the single most important tool used in quality control, in particular for analyzing variations in a process, is a control chart. A control chart is an effective means for discovering and correcting the assignable causes of variation outside the pattern of random causes.
