定义 Definition: Law of diminishing marginal returns 边际收益递减法则

At a certain point, employing an additional factor of production causes a relatively smaller increase in output. 在某一点上，采用一个额外的生产要素会导致产出的相对较小的增加。

  • Diminishing returns occur in the short run when one factor is fixed (e.g. capital) 当一个因素是固定的（如资本），在短期内会出现收益递减。
  • If the variable factor of production is increased (e.g. labour), there comes a point where it will become less productive and therefore there will eventually be a decreasing marginal and then average product. 如果可变的生产要素增加（如劳动力），就会有一个点，它的生产力会降低，因此，最终会出现边际产品递减，然后是平均产品。
  • This is because, if capital is fixed, extra workers will eventually get in each other’s way as they attempt to increase production. For example, think about the effectiveness of extra workers in a small café. If more workers are employed, production could increase but more and more slowly. 这是因为，如果资本是固定的，额外的工人在试图增加生产时，最终会互相妨碍。例如，想想一个小咖啡馆里额外工人的效力。如果雇用更多的工人，产量可以增加，但会越来越慢。
  • This law only applies in the short run because, in the long run, all factors are variable. 这个定律只适用于短期，因为从长远来看，所有因素都是可变的。

The Law of diminishing marginal returns explained 边际收益递减法则解释

  • Assume the wage rate is ￡10, then an extra worker costs ￡10. 假设工资率是10英镑，那么一个额外的工人要花费10英镑。
  • The Marginal Cost (MC) of a sandwich will be the cost of the worker divided by the number of extra sandwiches that are produced 一个三明治的边际成本（MC）将是工人的成本除以额外生产的三明治数量。
  • Therefore as MP increases MC declines and vice versa 因此，随着MP的增加，MC会下降，反之亦然。
  • Total Product (TP) This is the total output produced by workers 总产品（TP） 这是工人生产的总产出。
  • Marginal Product (MP) This is the output produced by an extra worker. 边际产品（MP） 这是一个额外工人生产的产出。

  • The first worker adds two goods. If a worker costs ￡20. The MC of those two units is 20/2 = 10. 第一个工人增加了两个货物。如果一个工人的成本是20英镑。这两个单位的MC是20/2=10。
  • The 3rd worker adds six goods. The MC of those six units are 20/6 = 3.3 第三个工人增加了六件货物。这六个单位的MC是20/6=3.3。
  • The 5th worker adds an extra ten goods. The MC of these 10 is just 2. 第5个工人又增加了10件货物。这10件商品的MC只有2。
  • After the 5th worker, diminishing returns sets in, as the MP declines. As extra workers produce less, the MC increases. 在第5个工人之后，随着MP的下降，收益递减的现象开始出现。随着额外的工人生产的产品减少，MC也会增加。

Diagram of diminishing returns 收益递减的示意图

  • In this example, after three workers, diminishing returns sets in. 在这个例子中，在三个工人之后，收益递减的情况出现了。
  • After employing 4 workers or more – the marginal product (MP) of the worker declines and the marginal cost (MC) starts to rise. 在雇用4名工人或更多之后，工人的边际产品（MP）下降，边际成本（MC）开始上升。

Difference between diminishing returns and dis-economies of scale 收益递减和规模不经济之间的区别

  • Diminishing returns relate to the short run – higher SRAC. Diseconomies of scale is concerned with the long run. Diseconomies of scale occur when increased output leads to a rise in LRAC – e.g. after Q4, we get a rise in LRAC. 收益递减与短期有关--较高的SRAC。规模不经济是指长期的。当产量增加导致LRAC上升时，就会出现规模不经济，例如，在第四季度之后，我们会得到LRAC的上升。
  • At output Q1, we get diminishing returns, shown by SRAC1. 在产出第1季度，我们会得到递减的回报，如SRAC1所示。
  • If the factory, increases capital, we can get a different outcome, shown by SRAC2. But, we still get diminishing returns in the short run. 如果工厂增加资本，我们可以得到一个不同的结果，如SRAC2所示。但是，我们在短期内仍然得到递减的回报。

Examples of diminishing returns 回报递减的例子

  • Use of chemical fertilisers 使用化肥. A good example of diminishing returns includes the use of chemical fertilisers- a small quantity leads to a big increase in output. However, increasing its use further may lead to declining Marginal Product (MP) as the efficacy of the chemical declines. 递减收益的一个很好的例子是使用化肥--少量的化肥会导致产量的大幅增加。然而，进一步增加其使用可能会导致边际产品（MP）下降，因为化学品的功效下降。
  • Revising into the early hours of the morning 复习到凌晨时分. If you revise economics for six hours a day, you will improve your knowledge quite a bit. However, if you continue to revise into the early hours of the morning, the amount that you learn increases by only a small amount because you are tired. 如果你每天复习经济学六个小时，你的知识会有相当大的提高。然而，如果你继续复习到凌晨，你学到的知识只增加了一小部分，因为你很累。
  • Employing extra workers 雇用额外的工人. A cafe may wish to serve more customers during the busy summer months. However, employing extra workers may be difficult because of a lack of space in the cafe. 一家咖啡馆可能希望在繁忙的夏季为更多顾客服务。然而，由于咖啡馆缺乏空间，雇用额外的工人可能是困难的。

Diminishing marginal returns to wealth 财富的边际收益递减

Another example of diminishing marginal returns could be with regard to wealth. As your wealth increases, initially, your happiness rises as you are able to buy food to eat and a place to live. But, after a certain level of wealth, gaining more wealth doesn’t lead to any rise in happiness. As the old saying goes “money can’t buy happiness”. 边际收益递减的另一个例子可能是关于财富的。随着你的财富增加，最初，你的幸福感会上升，因为你能买到吃的和住的地方。但是，在财富达到一定水平后，获得更多的财富并不会导致幸福感的上升。正如老话所说，&34;金钱买不到幸福&34;。