Process control methods, in general, and quality, in particular, most often refer to the measures taken especially to the finished product, as well as to the technological process, in order to maintain its performance within certain statistical parameters. Genichi Taguchi is the first who...

Walter Andrew Shewhart is regarded as the founder of Statistical Quality Control (SQC), an approach to production inspection based on the application of statistical theory. He developed SQC in the 1920s while working at Bell Telephone Laboratories. During this period, he was tasked with training...

Historical investment performance is most commonly displayed as a charted time series of what are referred to simply as “growth” returns. Unfortunately, charts of such returns have a number of shortcomings that can severely limit their value as a means of providing investors with a...

In recent years, there has been a resurgence in the development of control charts for monitoring the mean of the ratio of two correlated variables. However, most of the existing research has focused on the univariate mean of the ratio of two correlated variables under the assumption that the...