ABSTRACT

Statistical quality control is based on the premise that there is always a chance that a manufacturing process will not produce as intended. Nothing is certain to happen –the unexpected may occur at any time. The rules and theory of statistical probability permit quality control personnel to evaluate the chance that defective material will appear in a process or a product. There are two basic rules for probability. These are the addition and the multiplication rules. The addition rule is used when the probability of one event or another event will occur. The multiplication rule is used when the probability of one event and another will occur. This chapter examines the concept of probability –the chance that an ever increasing event will occur. The basic addition and multiplication rules governing empirical or observed probabilities have been explained as they relate to quality control applications.