Control charts are extensively used in manufacturing contexts to monitor production processes. This article illustrates economical design of a variable sample size and control limit Hotelling’s T2 control chart based on a novel cost model when occurrence times of the assignable causes are...

Over the span of a decade, the spectrum of online activities has expanded worldwide. From casual browsing to social networking, from education to entertainment, and from engaging in commercial to philanthropic pursuits, the array of online activities has continued to diversify in scope. Some...

This paper shows the effects of the COVID-19 pandemic on energy markets. We estimate daily volatilities and correlations among energy commodities relying on a mixed-frequency approach that exploits information from the number of weekly deaths related to COVID-19 in the United States. The...