profit per barrel of oil The accounting income follows the historical cost principle and the matching principle, which is conducive to the objective reflection of the business management responsibility of the enterprise management authorities. But, due to the historical cost principle inherent defects, especially according to the present value of revenue and expenses by historical cost line, makes the calculation of accounting earnings lack of inner logical unity, and the matching principle is difficult to carry out, so that the book value of assets can not reflect its real value, cost cannot be fully compensated. And the economic benefit is measured in the current value, which reflects the actual value of the asset, which is beneficial to the full compensation of the cost. Positive economic profit is sometimes described as excess profit. advertising The difference between financial capital preservation and physical capital preservation According to this model, the interest rate decision depends on the supply of savings and investment needs, money supply, money demand, four factors, cause a change in the saving investment, money supply and demand factors will affect the level of interest rates. This theory is characterized by general equilibrium analysis.