Give opinion: Managers must make critical economic decisions every day, such as whether to make or buy their products, if they should take or leave an offer on the table, or between different projects to determine which is more profitable. Contribution analysis is a cost-benefit method of decision making that evaluates the financial contribution of each decision to an organization's profit and overhead (after covering the variable costs involved) by estimating the incremental costs and revenues involved, performed with the goal of profit-maximization. When deciding the overall contribution of each potential choice, it is crucial to consider all of the costs and revenues involved (but only those that vary as a result of the decision). Therefore, contribution analysis ignores fixed overhead costs since managers are only concerned if the decision increases profit (or not) and by how much. Then, a sensitivity analysis of the resulting conclusion can measure how much the overhead could change without altering the decision made (Douglas, 2012).

3. CES Aggregate Production Function The Constant Elasticity of Substitution (CES) production function is gaining popularity in the economics literature. Duffy and Papageorgiou (2000) use this production function. Suppose the aggregate production function is given by: Y = A((1 - B) Ke + BNP) VP where A is TFP, K and N are capital and labour inputs, and 0