📚 Monopsony in the Labour Market | 劳动市场中的买方垄断
A monopsony exists when there is a single buyer in a market. In the labour market, a monopsony employer is the only or dominant buyer of labour, which gives the firm wage-setting power. For A-Level Economics, monopsony is a key market failure because it can lead to lower wages and lower employment than in a competitive labour market.
买方垄断是指市场上只有一个买家。在劳动市场中，买方垄断雇主是唯一或占主导地位的劳动力购买者，这使企业拥有设定工资的力量。对于 A-Level 经济来说，买方垄断是一个重要的市场失灵，因为它可能导致工资和就业低于竞争性劳动市场。
1. Defining Monopsony | 买方垄断的定义
A monopsony is a market structure with one buyer and many sellers. In the labour market, the buyer is the employer and the sellers are workers. A pure monopsony is rare, but many employers have monopsony power because workers face barriers to moving or limited alternative job offers.
买方垄断是一种只有一个买家和许多卖家的市场结构。在劳动市场中，买家是雇主，卖家是工人。纯粹的买方垄断很少见，但许多雇主拥有买方垄断力量，因为工人面临流动障碍或有限的其他工作机会。
Monopsony power means the employer can influence the wage rate by changing the number of workers it hires. This is different from a perfectly competitive labour market, where each firm is a wage taker.
买方垄断力量意味着雇主可以通过改变雇佣工人数量来影响工资率。这与完全竞争劳动市场不同，在完全竞争中每个企业都是工资接受者。
2. Characteristics and Sources of Monopsony Power | 买方垄断力量的特征与来源
Monopsony power can arise from several sources. First, geographical immobility means workers in a town dominated by one large employer, such as a factory or hospital, have few local alternatives. Second, occupational immobility limits workers to a narrow skill set, making it costly to switch industries.
买方垄断力量可以来自几个来源。第一，地域不流动性意味着在一个由一家大雇主主导的城镇中，例如工厂或医院，工人几乎没有本地其他选择。第二，职业不流动性限制了工人只能从事狭窄的技能范围，使转换行业的成本很高。
Third, barriers to entry for firms can protect an existing dominant employer. Fourth, collusion between employers, such as no-poaching agreements, can reduce competition for workers. Finally, information failure may prevent workers from knowing about better-paid jobs elsewhere.
第三，企业的进入壁垒可以保护现有的主导雇主。第四，雇主之间的合谋，例如不挖人协议，可以减少对工人的竞争。最后，信息失灵可能使工人不知道其他地方有更高薪的工作。
- Geographical immobility – 地域不流动性
- Occupational immobility – 职业不流动性
- Barriers to entry for firms – 企业进入壁垒
- Employer collusion – 雇主合谋
- Information failure – 信息失灵
3. The Firm’s Labour Supply Curve | 厂商面临的劳动供给曲线
In a competitive labour market, an individual firm can hire any number of workers at the market wage, so its labour supply curve is perfectly elastic. A monopsonist faces the market labour supply curve, which is upward sloping. To attract more workers, the monopsonist must offer a higher wage.
在竞争性劳动市场中，单个企业可以以市场工资雇佣任意数量的工人，因此其劳动供给曲线是完全弹性的。买方垄断者面临的是市场劳动供给曲线，它是向上倾斜的。为了吸引更多工人，买方垄断者必须提供更高的工资。
The wage paid to hire an extra worker is therefore not the marginal cost of labour. In a monopsony, if the firm raises the wage to recruit one additional worker, it must also raise the wage for all existing workers on the same contract. This makes the marginal cost of labour greater than the wage.
因此，雇佣额外工人的工资并不是劳动边际成本。在买方垄断中，如果企业提高工资以招聘一个额外工人，它也必须为同一合同下所有现有工人提高工资。这使得劳动边际成本高于工资。
Average labour cost (ALC) = wage = supply price
4. Marginal Cost of Labour | 边际劳动成本
The marginal cost of labour (MCL) is the additional total cost of hiring one more worker. For a monopsonist, MCL lies above the labour supply curve because hiring an extra worker raises the wage for all workers.
劳动边际成本（MCL）是雇佣一个额外工人所带来的总成本增加。对于买方垄断者来说，MCL 位于劳动供给曲线之上，因为雇佣一个额外工人会提高所有工人的工资。
If the total wage bill is TC = w(L) × L, then the marginal cost of labour can be written as:
如果总工资成本为 TC = w(L) × L，那么劳动边际成本可以写为：
MCL = ΔTC / ΔL
An equivalent expression is:
一个等价的表达式是：
MCL = w + L × (Δw / ΔL)
Here w is the wage, L is the number of workers, and Δw / ΔL is the slope of the labour supply curve. Since the supply curve slopes upward, Δw / ΔL is positive, so MCL is greater than w.
这里 w 是工资，L 是工人数量，Δw / ΔL 是劳动供给曲线的斜率。由于供给曲线向上倾斜，Δw / ΔL 为正，因此 MCL 大于 w。
5. Profit-Maximising Employment and Wage | 利润最大化雇佣与工资
A profit-maximising employer hires workers up to the point where the marginal revenue product of labour equals the marginal cost of labour. Marginal revenue product (MRPL) is the extra revenue from employing one more worker, calculated as marginal product of labour multiplied by marginal revenue.
利润最大化的雇主会雇佣工人直到劳动的边际收益产量等于劳动的边际成本。边际收益产量（MRPL）是雇佣一个额外工人带来的额外收入，它等于劳动边际产量乘以边际收益。
The equilibrium condition for the monopsonist is therefore:
因此，买方垄断者的均衡条件是：
MRPL = MCL
The monopsonist hires Lm workers, where the MRPL curve intersects the MCL curve. However, the wage is not read from the MCL curve. The firm pays the lowest wage needed to attract exactly Lm workers, which is found on the labour supply curve at Lm. This wage Wm is lower than the MRPL of the last worker.
买方垄断者雇佣 Lm 个工人，即 MRPL 曲线与 MCL 曲线相交之处。然而，工资不是从 MCL 曲线上读取的。企业支付正好吸引 Lm 个工人所需的最低工资，这由 Lm 处的劳动供给曲线决定。这个工资 Wm 低于最后一个工人的 MRPL。
Economists sometimes describe this as monopsonistic exploitation because workers are paid less than the value of their marginal product.
经济学家有时将这种情况称为买方垄断剥削，因为工人获得的报酬低于其边际产品的价值。
6. Comparing Monopsony with Perfect Competition | 与完全竞争的比较
In a perfectly competitive labour market, the equilibrium occurs where market labour demand equals market labour supply. The wage is Wc and employment is Lc. Each firm hires where MRPL equals the market wage, and MCL equals the wage because the firm is a wage taker.
在完全竞争劳动市场中，均衡出现在市场劳动需求等于市场劳动供给之处。工资为 Wc，就业为 Lc。每个企业雇佣到 MRPL 等于市场工资之处，且 MCL 等于工资，因为企业是工资接受者。
A monopsonist hires fewer workers and pays a lower wage than the competitive outcome. At Lm, the marginal revenue product of labour is above the wage, but the firm stops hiring because the marginal cost of labour is even higher.
买方垄断者比竞争结果雇佣更少的工人并支付更低的工资。在 Lm 处，劳动的边际收益产量高于工资，但企业停止雇佣是因为劳动边际成本更高。
| Outcome – 结果 | Perfect competition – 完全竞争 | Monopsony – 买方垄断 |
| Wage – 工资 | Wc | Wm, lower – 更低 |
| Employment – 就业 | Lc | Lm, lower – 更低 |
| MCL – 劳动边际成本 | Equals wage – 等于工资 | Greater than wage – 高于工资 |
7. Minimum Wage in a Monopsony | 买方垄断下的最低工资
In a competitive labour market, a minimum wage above the equilibrium wage tends to reduce employment, other things being equal. However, in a monopsony labour market, a well-chosen minimum wage can increase both wages and employment.
在竞争性劳动市场中，高于均衡工资的最低工资在其他条件不变时往往会减少就业。然而，在买方垄断劳动市场中，设置得当的最低工资可以同时提高工资和就业。
If the government sets a minimum wage Wmin between the monopsony wage Wm and the competitive wage Wc, the monopsonist becomes a wage taker up to the quantity of labour willing to work at Wmin. The marginal cost of labour becomes equal to Wmin over that range, so the firm hires more workers than before.
如果政府将最低工资 Wmin 设定在买方垄断工资 Wm 与竞争工资 Wc 之间，买方垄断者就成为一个工资接受者，直到愿意在 Wmin 工作的劳动数量为止。在这一范围内，劳动边际成本等于 Wmin，因此企业比以前雇佣更多工人。
The profit-maximising condition is now MRPL = Wmin, so employment can rise to Lmin. A minimum wage set too high, above the competitive wage, can still reduce employment because MRPL is less than the cost of labour at that quantity.
此时利润最大化条件为 MRPL = Wmin，因此就业可以上升到 Lmin。如果最低工资设定得过高，高于竞争工资，仍然可能减少就业，因为在该数量下 MRPL 低于劳动成本。
This is a powerful evaluation point in exams: the impact of a minimum wage depends on labour market structure.
这是考试中的一个有力评估要点：最低工资的影响取决于劳动市场结构。
8. Trade Unions and Bilateral Monopoly | 工会与双边垄断
A trade union is an organisation that represents workers and aims to improve pay and conditions. A union can act as a monopoly seller of labour, offsetting the employer’s monopsony power. When a single seller of labour faces a single buyer of labour, the market is a bilateral monopoly.
工会是代表工人并旨在改善薪酬和工作条件的组织。工会可以作为劳动的垄断卖方，抵消雇主的买方垄断力量。当单一的劳动卖方面对单一的劳动买方时，该市场就是双边垄断。
In a bilateral monopoly, the wage outcome is not determined by a single intersection. The union may bargain for a higher wage, while the monopsonist may use its buying power to hold wages down. The final wage depends on the relative bargaining strength of each side.
在双边垄断中，工资结果不是由单一交点决定的。工会可能争取更高的工资，而买方垄断者可能利用其购买力压低工资。最终工资取决于双方的相对议价能力。
Unions can help correct monopsony exploitation by negotiating wages closer to the competitive level. However, if unions push wages too high, employment may fall, especially if the firm cannot pass on higher costs.
工会可以通过谈判将工资推向接近竞争水平，从而帮助纠正买方垄断剥削。然而，如果工会将工资推得过高，就业可能下降，尤其是当企业无法转嫁更高成本时。
9. Efficiency and Welfare Effects | 效率与福利影响
Monopsony causes allocative inefficiency because employment is below the competitive level. At Lm, the marginal benefit to the firm, measured by MRPL, is greater than the marginal cost to workers of supplying labour, measured by the supply curve. This creates a deadweight welfare loss.
买方垄断导致配置无效率，因为就业低于竞争水平。在 Lm 处，以 MRPL 衡量的企业边际收益大于以供给曲线衡量的工人提供劳动的边际成本。这会造成无谓福利损失。
Monopsony also redistributes income from workers to employers. Workers receive lower wages, while the firm earns higher profits by holding down labour costs. This can worsen income inequality in a local labour market.
买方垄断还将收入从工人重新分配给雇主。工人获得较低工资，而企业通过压低劳动成本获得更高利润。这会加剧当地劳动市场的收入不平等。
Dynamic efficiency may also be affected. On one hand, lower labour costs can boost profits and investment. On the other hand, low wages may reduce worker motivation, productivity and labour supply quality over time.
动态效率也可能受到影响。一方面，较低的劳动成本可以提高利润和投资。另一方面，低工资可能随着时间推移降低工人积极性、生产率和劳动供给质量。
10. Evaluation and Exam Tips | 评估与考试技巧
In exam answers, it is important to recognise that pure monopsony is rare. Many employers have some monopsony power, but they still face competition from other firms, self-employment and migration. The degree of monopsony power depends on the elasticity of labour supply.
在考试答案中，重要的是认识到纯粹买方垄断很少见。许多雇主拥有一定程度的买方垄断力量，但他们仍然面临来自其他企业、自雇和移民的竞争。买方垄断力量的程度取决于劳动供给的弹性。
If labour supply is inelastic, workers have few alternatives, so monopsony power is strong. If labour supply is elastic, workers can move to other jobs easily, so the employer’s power is weak. Government policy, such as training, transport and information, can increase labour supply elasticity and reduce monopsony exploitation.
如果劳动供给缺乏弹性，工人的选择很少，因此买方垄断力量很强。如果劳动供给有弹性，工人可以轻松转向其他工作，因此雇主的力量较弱。政府政策，如培训、交通和信息，可以提高劳动供给弹性并减少买方垄断剥削。
When evaluating a minimum wage, students should distinguish between a competitive market and a monopsony market. They should also consider the level of the minimum wage, the profitability of firms, the time period, and possible effects on prices, productivity and unemployment in related sectors.
在评估最低工资时，学生应区分竞争市场和买方垄断市场。他们还应考虑最低工资水平、企业的盈利能力、时间周期，以及对相关行业价格、生产率和失业的可能影响。
A strong A-Level answer will use a diagram showing MRPL, MCL and the labour supply curve, label Wc, Lc, Wm and Lm, and explain why a minimum wage can raise employment. It will also mention real-world examples such as a single hospital in a remote area, a dominant mining company, or a large retailer in a small town.
一个优秀的 A-Level 答案会使用显示 MRPL、MCL 和劳动供给曲线的图表，标注 Wc、Lc、Wm 和 Lm，并解释为什么最低工资可以提高就业。它还会提到现实例子，如偏远地区的单一医院、占主导地位的矿业公司，或小镇上的大型零售商。
Published by TutorHao | Economics Revision Series | aleveler.com
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