This chapter discusses standard deviation as a statistical tool that can be applied to calculate lost profits. The answers for questions regarding mean, median and data distribution help in determining which statistical tool should be used for the purpose of calculating lost profits. Aforementioned questions can find their answers in the form of histograms, stem and leaf plots and box plots as well as in Excel functions. The knowledge gained from these answers enables data to be compared with contemporaneous variables. This is how one can employ standard deviation where data set is a sample instead of population. The data set can be classified as either sample or population on the basis of the scope of inferences made out of it.