A Computer Program to Calculate Two-Stage Short-Run Control Chart Factors for (X,MR) Charts

Abstract

This paper is the second in a series of two papers that fully develops two-stage short-run (X, MR) control charts. This paper describes the development and execution of a computer program that accurately calculates first- and second-stage short-run control chart factors for (X, MR) charts using the equations derived in the first paper. The software used is Mathcad. The program accepts values for number of subgroups, α for the X chart, and α for the MR chart both above the upper control limit and below the lower control limit. Tables are generated for specific values of these inputs and the implications of the results are discussed. A numerical example illustrates the use of the program.

Keywords

• control chart
• short-run statistical process control
• two-stage control charting
• probability integral of the range
• probability integral of the studentized range
• distribution of the mean moving range