This is a very common methods of forecasting demand. Under this methods a relationship is established between quantity demanded( dependent variable) and independent variables such as income price of the good prices of the related goods etc. Once the relationship is established we derive regression equation assuming relationship to be linear. The equation will independent be of the form Y=A= BX. There could also be a curvy linear relationship between dependent and independent variable . once the regression equation is derived the value of y i, e, quantity demanded can be estimated for any given value of X.