There are some situations when the process mean fluctuates from time to time but is still considered as in-control and the process standard deviation is a linear function of the process mean. In addition, in some cases, the mean and the variance of a process are actually dependent on each other. In these situations, many researchers have suggested to monitor the CV (Coefficient of Variation) as a single statistic. In this paper, a rigorous content analysis method (based on 71 related studies in this area from 2007 to 2021) is applied to categorize the articles that use the coefficient of variation in the SPM (statistical process monitoring) field, to identify the research gaps and to provide guidance to stimulate further researches in this direction.