ABSTRACT
This chapter discusses the simple Shewhart control charts that use statistical parameters to define their control limits. A 4-sigma process has four standard deviations between its nominal and each specification limit, so there are eight standard deviations or “sigmas” between the specification limits. The simplest form of short-run SPC uses the deviation from the nominal method. Applications consist of processes with one set of specification limits and one process standard deviation. This chapter focuses only on the latter. The StatGraphics control chart was obtained from entry of all 50 simulated data, but what we need on the shop floor is a spreadsheet into which the inspector or production worker can enter measurements one at a time and get immediate feedback on whether an out of control signal has occurred.
