The CV can be used for several reasons in statistics and data analysis such as comparing variability, risk assessment, and quality control. Oftentimes, the CV is used to compare variability across data sets. One problem with the coefficient of variation is if the mean is 0 then the CV is not defined. Another issue is that if the mean is close to 0, then the estimated CV may be very noisy in the sense that small changes in the estimated mean can produce big changes in the CV. If one’s data only contains positive or negative values, then both issues are less likely.