The Assumptions of variable quality control charts and an application

ABSTRACT Master of Science Thesis THE ASSUMPTIONS OF VARIABLE QUALITY CONTROL CHARTS AND AN APPLICATION Sevil ŞENTÜRK Anadolu University Graduate School of Natural and Applied Sciences Statistics Program Supervisor: Prof. Embiya A?AO?LU 2002, 89 Pages In recent years, quality has become a priority for companies. Increased competition among companies has made them think more intensively about the quality aspects of their products. To get an idea of quality, quality control charts can be used and are helpful to decide if a product needs a specific quality standard. Statistics is the basis of quality control. Statistical techniques are used in many stages of the quality control process. Especially, quality control charts are the most common techniques used in companies. Quality control charts can easily picture the overall structure of the process. However, quality control charts are based on some assumptions to get valid answers. In many applications, it can be seen that checking these assumptions is neglected. The aim of this study is to investigate the assumptions of variable control charts. To check the assumptions, several statistical techniques are used and are explained in this study. In the application part of the study, the assumptions of the quality charts are carried out by the measurements of piston radius. Furthermore, x and R quality control charts are drawn. Keywords: Assumptions In Quality Control, Autocorrelation, Statistical Process Control, Quality Control Charts. 11