Advantages: (1) simple and clear, e

Advantages: (1) simple and clear, easy to calculate: (2) by the size of the workload depreciation, depreciation costs or the cost of production and operating revenue or production results and the reason: (3) for many asset depreciation change this assumption is reasonable, especially under the condition of physical wear and tear is more important than economic old especially drawbacks: (1) the annual depreciation charge is changing, but it assumes that the distribution of each work unit according to the same amount of depreciation is not root, and as a result of the existence of interest, asset service how to value the fact that a is not equivalent to reduce;(2) it is difficult to accurately estimate the number of jobs provided by the assets, and it is even more difficult to predict the life of depreciation in advanceIt is more difficult to estimate the useful life of an asset than the useful life; (3) factors such as invisible loss, increasing maintenance costs and operating efficiency are not taken into account.