A-level economics revision guides and question banks covering labour markets, supply and demand, market structure and all core economics a-level topics.
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今天带给大家Alevel经济笔记是：
第七章：劳动力市场——劳动力需求
The labour market is another topic that is becoming very popular with examiners.
Although many students find it more complicated than some of the previous macroeconomic topics, it is, as is so much in A level economics, simply an application of supply and demand.
劳动力市场是另一个越来越受考官欢迎的话题。尽管许多学生发现它比之前的一些宏观经济主题更复杂，但它就像 A Level 经济学中一样，只是供求关系的一种应用。
Before we get going, it is important that you understand how the labour market differs from the product market.
In the product market, the supply curve represents the firm's supply of the good in question and the demand curve represents the consumer's demand for the good.
With labour markets the roles are reversed; the demand curve represents the firm's demand for labour and the supply curve represents the consumer's (or worker's) supply of labour.
在我们开始之前，重要的是您要了解劳动力市场与产品市场的不同之处。在产品市场中，供给曲线代表企业对相关商品的供给，需求曲线代表消费者对商品的需求。在劳动力市场上，角色颠倒了；需求曲线代表企业对劳动力的需求，供给曲线代表消费者（或工人）的劳动力供给。
As with the product market, we will start with demand and supply, and then combine the two to get the equilibrium price and quantity (in this case, price is the wage rate and quantity is the quantity of labour).
与产品市场一样，我们将从需求和供给开始，然后将两者结合得到均衡价格和数量（在这种情况下，价格是工资率，数量是劳动力数量）。
The demand for labour is a derived demand对劳动力的需求是派生的需求The first point to note is that the demand for labour is a derived demand. Labour is only demanded as an input into the production process.
If the demand for the good in question changes then so will the demand for the labour that helps to make that product.
首先要注意的是，对劳动力的需求是派生需求。劳动力只需要作为生产过程的投入。如果对相关商品的需求发生变化，那么对有助于制造该产品的劳动力的需求也会发生变化。
In the product market, the demand curve is downward sloping.
As the price of a good falls, one would expect its demand to rise, ceteris paribus.
One would expect this to be the case in the labour market too. If the price of labour falls (i.e. the wage rate falls) one would expect a firm's demand for labour to rise, ceteris paribus.
If the price of labour were falling relative to, say, capital, then it would make sense for the firm to substitute labour for capital.
在产品市场上，需求曲线是向下倾斜的。随着一种商品的价格下跌，人们会预期它的需求会上升，在其他条件不变的情况下。人们预计劳动力市场也会出现这种情况。如果劳动力价格下降（即工资率下降），人们会预期公司对劳动力的需求会上升，在其他条件不变的情况下。如果劳动力的价格相对于资本下降，那么公司用劳动力代替资本是有意义的。
Of course, in the short run we assume that the amount of capital is fixed, but given the law of diminishing marginal returns (see the topic on 'Costs and revenues' for details), eventually, additional workers will be worth less to the firm than previous workers, and so their wage will be lower to reflect this fact.
So looking at it from a different angle, one would expect lower wage rates at higher employment levels; again the demand curve for labour ought to be downward sloping.
当然，在短期内，我们假设资本数量是固定的，但考虑到边际收益递减规律（详见“成本和收入”主题），最终，额外的工人对公司的价值会降低比以前的工人，所以他们的工资会更低，以反映这一事实。因此，从不同的角度来看，人们会预期更高的就业水平会降低工资率；再次，劳动力的需求曲线应该是向下倾斜的。
We need to look at this in more detail.
We can derive the demand curve for labour using something called Marginal revenue product theory.
我们需要更详细地研究这一点。我们可以使用称为边际收益产品理论的东西推导出劳动力的需求曲线。
Marginal revenue product theory边际收益产品理论Before we get going, we need to define some terms.
在开始之前，我们需要定义一些术语。
Marginal physical product (MPP):
This is the extra physical output produced by one extra worker.
边际实物产品（MPP）：这是由一名额外工人生产的额外实物产出。
Marginal revenue product (MRP):
This is the extra revenue gained by the firm as a result of employing one more worker.
If an extra worker adds 10 units to total output (his MPP), and they are sold for £5 each, then the MRP will be £50.
边际收益产品（MRP）：这是公司因雇用一名工人而获得的额外收入。如果一个额外的工人在总产量（他的 MPP）上增加 10 个单位，并且每个单位的售价为 5 英镑，那么 MRP 将为 50 英镑。
Hopefully you can see, then, that the following formula follows:希望你能看到，然后，下面的公式如下：
MRP = MPP times marginal revenue (MR)
MRP = MPP乘以边际收益（MR）
So for the example of the worker who produces 10 units, each sold for £5:
£50 = 10 times £5
因此，以生产 10 个单位的工人为例，每个单位售价 5 英镑：
50 英镑 = 10 乘以 5 英镑
In the analysis that follows, I will hopefully convince you that the marginal revenue product curve is the firm's demand curve for labour.
But first, as usual, we need to make some assumptions.
As with perfect competition in the product market, some of these assumptions are fairly unrealistic.
在接下来的分析中，我希望能让你相信边际收益产品曲线是企业的劳动力需求曲线。但首先，像往常一样，我们需要做出一些假设。与产品市场的完全竞争一样，其中一些假设是相当不现实的。
① Workers are homogenous. They have identical skills. This is a bit like the assumption of homogenous goods in the perfect competition model.
工人是同质的。他们有相同的技能。这有点像完全竞争模型中的同质商品假设。
② Firms are operating in a perfectly competitive product market.
The importance of this assumption is that, just as they have no control over the price they set, they also have no buying power when demanding labour.
They are price takers in the product market and 'wage' takers in the labour market.
Also, in perfectly competitive product markets, marginal revenue is constant and equal to price.
So the formula above becomes: MRP = MPP times price (which is constant).
企业在完全竞争的产品市场中运营。这一假设的重要性在于，正如他们无法控制自己设定的价格一样，他们在要求劳动力时也没有购买力。他们是产品市场的价格接受者和劳动力市场的“工资”接受者。此外，在完全竞争的产品市场中，边际收益是恒定的并且等于价格。所以上面的公式变成了：MRP = MPP 乘以价格（它是常数）。
③ For the time being, we assume that there are no trade unions. We are assuming that the labour market is competitive.
Trade unions distort this competitive labour market just as powerful firms (in monopoly or oligopoly) would with their superior buying power (buying labour, that is).
目前，我们假设没有工会。我们假设劳动力市场是竞争性的。工会扭曲了这个竞争激烈的劳动力市场，就像强大的公司（垄断或寡头垄断）以其优越的购买力（即购买劳动力）一样。
Deriving the demand curve for labour推导劳动力需求曲线We mentioned the law of diminishing marginal returns earlier.
Remember that this 'law' stated that, in the short run, "if a firm increases output by adding variable labour to fixed capital then eventually diminishing marginal returns (physical product of labour) will set in."
In other words, at some point an extra worker will add less output to the grand total than the previous worker.
我们前面提到了边际收益递减规律。请记住，该“定律”指出，在短期内，“如果一家公司通过在固定资本中增加可变劳动力来增加产出，那么最终边际收益递减（劳动的实物产品）将开始出现。” 换句话说，在某些时候，一个额外的工人将比前一个工人在总产量中增加更少的产出。
So I think it is fair to say that the marginal physical product curve will look exactly the same as the marginal returns curve that we used in the 'Costs and revenues' topic They are, basically, the same thing. We can now derive the MRP curve.
所以我认为可以公平地说，边际实物产品曲线看起来与我们在“成本和收入”主题中使用的边际收益曲线完全相同。它们基本上是一样的。我们现在可以推导出 MRP 曲线。
Notice in the diagram above that the shape of the MRP curve is exactly the same as the shape of the MPP curve. The only difference is the scale on the y-axis.
Every value for the output in the middle diagram has been multiplied by £5 (given in the diagram on the right) to give the values on the y-axis in the diagram on the left.
请注意，在上图中，MRP 曲线的形状与 MPP 曲线的形状完全相同。唯一的区别是 y 轴上的刻度。中间图中输出的每个值都乘以 5 英镑（在右图中给出），得到左图中 y 轴上的值。
So, the MRP curve is derived from the MPP curve, which is derived from the law of diminishing marginal returns.
所以，MRP曲线是从MPP曲线推导出来的，MPP曲线是从边际收益递减规律推导出来的。
Now, why is the MRP curve the demand curve for labour for each of these perfectly competitive firms?
现在，为什么 MRP 曲线是每个完全竞争企业的劳动力需求曲线？
Earlier, we assumed that the labour market that we are dealing with is competitive.
This means that the wage is constant.
Firms can employ as many workers as they want at the given wage, just like they can sell as many goods as they want at the given price in perfectly competitive product markets.
We can call the wage the marginal factor cost (MFC).
Factor, meaning factor of production (in this case, labour). So the MFC is the extra cost to the firm of employing one more worker.
早些时候，我们假设我们正在处理的劳动力市场是竞争性的。这意味着工资是不变的。企业可以以给定的工资雇佣任意数量的工人，就像他们可以在完全竞争的产品市场上以给定的价格出售任意数量的商品一样。我们可以将工资称为边际要素成本（MFC）。要素，意思是生产要素（在这种情况下是劳动力）。因此，MFC 是公司雇佣一名工人的额外成本。
Look at the diagram above. I've drawn an MRP curve and three MFC curves. Firms in product markets maximise profits at the level of output where marginal cost = marginal revenue (MC = MR).
If you can't remember why this is the case, I seriously advise you to look at the 'Costs and revenues' topic.
The same concept can be applied in the labour market.
Firms will employ labour up to and including the point where the extra revenue gained from the last unit of labour is the same as the extra cost of employing it.
In other words, where MRP = MFC.
看上面的图表。我画了一条 MRP 曲线和三条 MFC 曲线。产品市场中的企业在边际成本 = 边际收益 (MC = MR) 的产出水平上实现利润最大化。如果您不记得为什么会这样，我强烈建议您查看“成本和收入”主题。同样的概念也适用于劳动力市场。企业将雇用劳动力，直至并包括从最后一个劳动力单位获得的额外收入与雇用它的额外成本相同的点。换句话说，其中 MRP = MFC。
So, when the given wage is W1, this occurs at point A, giving an employment level of L1.
At wage rate W2, MRP = MFC occurs at point B, giving an employment level of L2, and at W3, for the same reason, L3 units of labour will be employed.
At each given price (wage rate) the firm reads his demand (for labour) from the MRP curve.
This is a pretty good definition of a demand curve!
The MRP curve is the demand curve for labour.
因此，当给定工资为 W 1时，这发生在 A 点，就业水平为 L 1。在工资率 W 2下，MRP = MFC 出现在 B 点，就业水平为 L 2，并且在 W 3下，出于同样的原因，将使用 L 3个单位的劳动力。在每个给定的价格（工资率）下，企业从 MRP 曲线中读取他的需求（劳动力）。这是对需求曲线的一个很好的定义！MRP曲线是劳动力的需求曲线。
What if the firm is not operating in a perfectly competitive goods market?如果公司不是在完全竞争的商品市场上运营怎么办？In the analysis above, we assumed that the firm was operating in a perfectly competitive goods market.
This meant that its marginal revenue curve was constant and equal to its price.
Hence, the formula MRP = MPP times MR became MRP = MPP times price.
在上面的分析中，我们假设公司在完全竞争的商品市场中运营。这意味着它的边际收益曲线是恒定的并且等于它的价格。因此，公式 MRP = MPP 乘以 MR 变为 MRP = MPP 乘以价格。
But most firms operate in an imperfectly competitive goods market (particularly oligopoly and monopoly).
This means that they face a downward sloping demand curve in the product market.
Seeing as the marginal revenue curve must be below a falling demand curve (which is the average revenue curve, remember) and falling twice as fast, this will affect the MRP formula quite a lot.
Luckily, it does not affect the fact that the MRP curve is downward sloping. In fact, it just means that the MRP curve is even steeper.
MRP = MPP times MR.
If MPP is falling (due to diminishing marginal returns) and MR is falling, then MRP must be falling too.
但大多数公司在不完全竞争的商品市场（特别是寡头垄断和垄断）中运营。这意味着他们在产品市场上面临着向下倾斜的需求曲线。看到边际收益曲线必须低于下降的需求曲线（记住，这是平均收益曲线）并且下降速度是两倍，这将对 MRP 公式产生很大影响。幸运的是，它不会影响 MRP 曲线向下倾斜的事实。事实上，它只是意味着 MRP 曲线更加陡峭。MRP = MPP 乘以 MR。如果 MPP 正在下降（由于边际收益递减）并且 MR 正在下降，那么 MRP一定也在下降。
Hence, the firm's demand curve for labour will be downward sloping whatever type of goods market the firm happens to be involved with.
因此，无论该公司碰巧涉及何种类型的商品市场，该公司的劳动力需求曲线都将向下倾斜。
The determinants of the elasticity of the demand for labour劳动力需求弹性的决定因素When we looked at the demand curve in the product market, its elasticity was important. In turn, it was important to assess what determined the value of the elasticity.
We must do the same thing with the demand curve for labour. Remember that elastic demand curves are relatively flat, so for a given change in the wage rate the proportionate change in the demand for labour will be larger.
Inelastic demand curves are relatively steep, so for a given change in the wage rate the proportionate change in the demand for labour will be much smaller.
当我们观察产品市场的需求曲线时，它的弹性很重要。反过来，评估决定弹性值的因素也很重要。我们必须对劳动力的需求曲线做同样的事情。请记住，弹性需求曲线相对平坦，因此对于给定的工资率变化，劳动力需求的比例变化将更大。无弹性的需求曲线相对陡峭，因此对于给定的工资率变化，劳动力需求的成比例变化将小得多。
Many of these determinants are similar in character to those for the demand in the product market. Check back in the 'Elasticity' topic to see if you agree.
其中许多决定因素在性质上与产品市场需求的决定因素相似。再次查看“弹性”主题，看看您是否同意。
① Availability of substitutes:
In the product market, if a good had lots of substitutes then its demand was more elastic.
This is true of labour too. The more substitutes there are, in terms of factor inputs (capital, in particular), then the more elastic the demand for labour will be.
替代品的可用性：在产品市场上，如果一种商品有很多替代品，那么它的需求就更有弹性。劳动也是如此。就要素投入（尤其是资本）而言，替代品越多，劳动力需求的弹性就越大。
② Labour costs as a proportion of total cost:
In the product market, if a good was very cheap, and so made up a very small proportion of a consumer's income, then its demand was relatively inelastic.
The same is true of labour costs.
If labour costs are a small proportion of total costs (perhaps at a nuclear plant) then the demand curve for labour will be relatively inelastic.
劳动力成本占总成本的比例：在产品市场上，如果一种商品非常便宜，因此在消费者收入中所占的比例很小，那么它的需求就相对缺乏弹性。劳动力成本也是如此。如果劳动力成本占总成本的一小部分（可能在核电站），那么劳动力需求曲线将相对缺乏弹性。
③ The derived demand factor:
Remember that labour is a derived demand. It makes sense, therefore, that the elasticity of demand for labour will be greatly affected by the elasticity of demand for the good that the labour is producing.
If the product in question has relatively inelastic demand (e.g. petrol) then the demand for those working in the industry will also be fairly inelastic (e.g. workers at an oil rig).
派生需求因素：请记住，劳动力是派生需求。因此，劳动力需求弹性将受到劳动力生产的商品需求弹性的极大影响是有道理的。如果所讨论的产品具有相对缺乏弹性的需求（例如汽油），那么对该行业从业人员的需求也将是相当缺乏弹性的（例如石油钻井平台的工人）。
④ The time factor:
As with all elasticity's, the longer the time period in question, the higher the value of the elasticity. In this case, the longer the time period, the easier it is to substitute labour for capital.
Also, in the short term, employers may be bound by contracts.
It the short term, therefore, it is difficult for a firm to vary the number of workers regardless of the wage rate.
Over the long run, though, the demand curve will be more elastic.
时间因素：与所有弹性一样，所讨论的时间段越长，弹性值就越高。在这种情况下，时间越长，就越容易用劳动力代替资本。此外，在短期内，雇主可能会受到合同的约束。因此，在短期内，无论工资率如何，公司都很难改变工人数量。不过，从长期来看，需求曲线将更具弹性。
今天的Alevel经济笔记就更新到这里，如果大家对Alevel经济学感兴趣可以关注我们，
关于Alevel经济笔记第7章：劳动力市场后续的更新计划如下：