Attribute inspection control charts for the joint monitoring of mean and variance

• Published in: Computers & industrial engineering Vol. 139; p. 106131
• Main Authors: Quinino, R.C., Cruz, F.R.B., Ho, L.L.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2020
• Subjects: Attribute and variable control charts; Average run length; Control charts; Noncentral Chi-square chart; Quality control; Attribute and variable control charts; Noncentral Chi-square chart; Average run length; Quality control; Control charts
• ISSN: 0360-8352; 1879-0550
• DOI: 10.1016/j.cie.2019.106131

•Using attribute instead of variable data for the control of the mean and variance.•Replacing attribute data with random values originated from a truncated normal.•Utilizing control limits for variables in attribute control.•Analyzing the effect on the ARL when attributes are used instead of variables.•Simulation studies to evaluate when to substitute variable data for attribute data. Novel control charts that are based on the inspection of attributes and use traditional control limits are proposed for the joint monitoring of mean and variance. The main advantage is that it is easier and cheaper to perform an attribute inspection than to obtain the actual values of the quality of interest in a variable-type inspection. The charts introduced here are tested through Monte Carlo simulations, and their efficiency confirmed, despite requiring larger sample sizes. Because the new control charts use attributes, which are easier to determine than physical measurements, they can be considered a competitive alternative to the traditional approach. A numerical example is presented to illustrate the use of the new tool and demonstrate its ease of use.