This chapter poses a problem in the form of determination of extent of semi- fixed cost to be deducted from lost revenues. It further discusses the process by which extent of semi fixed expense that varies with any variation in level of sales can be determined. The process begins with graphing the data, goes on with regression summary output of the first model, search for other independent variables and regression summary output of the second model. However, the result could be too practically insignificant to be a part of calculation of lost profits. At times, R² for regression model is low to the extent that there is a possibility of other independent variables missing. In such a case, sales coefficient is tested for statistical significance in context with other predictor variables if it is to form a part of calculation of lost profits.