Quasi-experiments on process dynamics


Davit Khachatryan, PricewaterhouseCoopers LLP, Suite 800W, 1301 K Street NW, Washington DC 20005, USA.
E-mail: davit.khachatryan@us.pwc.com


Summary.  It is often important to develop an understanding of the dynamic properties of a process. However, it is sometimes difficult if not impossible to conduct deliberate experiments on full-scale industrial plants and processes to gain such insight. Fortunately, intentional or inadvertent process changes that occur in the course of normal operation sometimes offer an opportunity to identify and estimate aspects of the dynamic behaviour. We review the theory of dynamic process modelling based on time series intervention analysis and show how this body of theory can be used for an assessment of the dynamic properties of a process. The ideas are accompanied by a detailed example of the study of a large-scale ceramic plant that was exposed to an intentional but unplanned structural change.