p chart control limits based on a small number of subgroups

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.The classical Shewhart p chart procedure requires data from at least 20 subgroups for setting up valid control limits, when the true fraction nonconforming of the process is unknown. This data requirement has prevented the use of p charts in short run situations and during the early stages of a production run. This thesis offers a solution to this issue by proposing a method for setting up p chart control limits even when the data available is from only a small number of subgroups. The run length performance of the proposed method has been experimentally compared with two other methods. The applicability of these methods to a short run situation has also been assessed experimentally. The proposed method has been found to detect shifts in the process fraction nonconforming more often than the other two methods, while increasing the rate of false alarms by only a small amount