Standardized p control charts for short runs

In situations where a quality characteristic cannot be measured conveniently or economically, it is common to count each item as either conforming or nonconforming to the specifications on that characteristic. Attribute control charts, especially p charts for fractions of nonconforming items, have been used widely for statistical process control of attribute characteristics. They are important tools because: attribute characteristics exist in many industrial and administrative processes; attribute data are frequently already available; in general, attribute data are quick and inexpensive to collect (see, e.g. [1, 2]).

When the process fraction of nonconforming items p is unknown, a...