📚 Monopsony Effects in the Labour Market | 劳动力市场的买方垄断效应
A labour market is rarely a perfectly competitive market. In many real-world situations, a single or dominant employer controls the demand for workers in a given region or industry. This market structure is known as monopsony, and it produces outcomes that differ significantly from those predicted by the standard supply-and-demand model. This article explores the nature of monopsony in the labour market, its effects on wages and employment, and the policy implications for students of CIE A-Level Economics.
劳动力市场很少是一个完全竞争的市场。在许多现实情境中，单一或占主导地位的雇主控制着特定地区或行业对工人的需求。这种市场结构被称为买方垄断（monopsony），它所产生的结果与标准供需模型所预测的情况有显著不同。本文将探讨劳动力市场中买方垄断的性质、其对工资和就业的影响，以及对 CIE A-Level 经济学学生的政策含义。
1. Defining Monopsony in the Labour Market | 劳动力市场中买方垄断的定义
A monopsony exists when there is a single buyer of a good or service. In the labour market, a monopsonist is the sole or dominant employer of a particular type of labour. Because workers have few alternative employment opportunities, the monopsonist possesses significant market power over the wage it pays. The classic textbook example is that of a company town, where one large employer, such as a mining company or a factory, is the only significant source of jobs in the local area.
当某种商品或服务只有一个买方时，就存在买方垄断。在劳动力市场中，买方垄断者是某一特定类型劳动力的唯一或占主导地位的雇主。由于工人几乎没有其他就业机会，买方垄断者在所支付的工资方面拥有巨大的市场力量。教科书中经典的例子是“公司镇”（company town），即一家大型雇主，如矿业公司或工厂，是当地唯一重要的就业来源。
It is important to distinguish monopsony from monopoly. A monopoly is a single seller in the product market, whereas a monopsony is a single buyer in the factor market. The two can coexist: a firm may be a monopolist in selling its output and a monopsonist in hiring its inputs. This article concentrates solely on the labour (factor) market dimension.
区分买方垄断与卖方垄断非常重要。垄断（monopoly）是产品市场中的单一卖方，而买方垄断（monopsony）是要素市场中的单一买方。两者可以同时存在：一家企业既可能是其产品出售时的垄断者，也可能是其投入品雇佣时的买方垄断者。本文仅聚焦于劳动力（要素）市场这一维度。
2. Key Assumptions of the Monopsony Model | 买方垄断模型的关键假设
The monopsony model in A-Level Economics rests on several key assumptions. First, the firm faces an upward-sloping labour supply curve, meaning that to attract additional workers it must offer a higher wage. Second, the firm is a wage-maker rather than a wage-taker; unlike a competitive firm that accepts the market wage as given, the monopsonist can influence wages through its hiring decisions. Third, the firm employs a homogeneous workforce and maximises profit by equating the marginal cost of labour with the marginal revenue product of labour.
A-Level 经济学中的买方垄断模型建立在若干关键假设之上。第一，企业面临一条向上倾斜的劳动力供给曲线，这意味着要吸引更多工人，它必须提供更高的工资。第二，企业是工资的制定者而非接受者；与接受既定市场工资的竞争性企业不同，买方垄断者可以通过其雇佣决策来影响工资。第三，企业雇佣同质化的劳动力，并通过使劳动力的边际成本等于劳动力的边际收益产品来实现利润最大化。
An additional critical assumption concerns the relationship between the supply curve and the marginal cost of labour. Because the firm pays the same wage to all workers, hiring one more worker forces the firm to raise the wage of every existing worker. The cost of the extra worker is therefore the new worker’s wage plus the wage increase for all existing employees. Consequently, the marginal cost of labour exceeds the wage at every level of employment.
另一个关键假设涉及供给曲线与劳动力边际成本之间的关系。由于企业向所有工人支付相同的工资，多雇佣一名工人迫使企业提高现有每一位工人的工资。因此，额外一名工人的成本等于新工人的工资加上所有现有员工的工资上涨。因此，在每个雇佣水平上，劳动力的边际成本都超过工资。
3. The Hiring Decision of a Monopsonist | 买方垄断者的雇佣决策
A profit-maximising monopsonist hires workers up to the point where the marginal cost of labour (MCL) equals the marginal revenue product of labour (MRP). Labour is demanded because it generates revenue; the MRP measures the additional revenue produced by the last worker hired. Hiring more workers increases total revenue, but also raises the wage bill. The optimal employment level is found where the extra cost equals the extra benefit.
追求利润最大化的买方垄断者会将工人的雇佣量确定在劳动力边际成本（MCL）等于劳动力边际收益产品（MRP）的水平。劳动力之所以被需求，是因为它能创造收入；MRP 衡量的是最后雇佣的一名工人所带来的额外收入。雇佣更多工人会增加总收入，但同时也会增加工资总额。最优雇佣水平出现在额外成本等于额外收益的地方。
Profit maximisation condition: MCL = MRP
利润最大化条件：MCL = MRP
Once the profit-maximising quantity of labour is determined, the wage is read off the labour supply curve at that quantity. Because the supply curve lies below the MCL curve, the wage paid is less than the MRP. This gap is often described as monopsonistic exploitation of labour. The firm is willing to hire workers at this lower wage because doing so is consistent with profit maximisation—paying a higher market wage to attract more workers would raise costs on all existing employees.
一旦确定了利润最大化的劳动量，工资就在该劳动量对应的劳动力供给曲线上读取。由于供给曲线位于 MCL 曲线下方，所支付的工资低于 MRP。这一差距通常被描述为对劳动的买方垄断剥削。企业愿意以较低的工资雇佣工人，是因为这样做符合利润最大化——支付更高的市场工资来吸引更多工人，将提高所有现有员工的成本。
4. Monopsony Equilibrium vs Perfect Competition | 买方垄断均衡与完全竞争均衡的比较
Comparing monopsony with perfect competition reveals the core inefficiency of the monopsonistic labour market. In a perfectly competitive labour market, the firm is a wage-taker; its labour supply curve is a horizontal line at the market wage, and the marginal cost of labour equals the wage. The competitive equilibrium occurs at the intersection of demand (MRP) and supply, producing a wage of W₁ and employment of Q₁.
将买方垄断与完全竞争进行比较，可以揭示买方垄断劳动力市场的核心低效率。在完全竞争的劳动力市场中，企业是工资接受者；其劳动力供给曲线是在市场工资水平的一条水平线，劳动力的边际成本等于工资。竞争性均衡出现在需求（MRP）与供给的交点，产生工资 W₁ 和就业量 Q₁。
In contrast, the monopsonist’s equilibrium occurs where MCL equals MRP, but the wage is set on the supply curve at that employment level. The resulting wage (W₂) is lower than the competitive wage W₁, and the employment level (Q₂) is lower than Q₁. Monopsony therefore leads to both lower wages and lower employment than a competitive market would achieve. This is a clear demonstration of market failure: resources (labour) are under-allocated to production.
相比之下，买方垄断者的均衡出现在 MCL 等于 MRP 之处，但工资在该雇佣水平上由供给曲线决定。由此产生的工资（W₂）低于竞争性工资 W₁，而就业水平（Q₂）低于 Q₁。因此，买方垄断导致的工资和就业水平都低于竞争性市场所能实现的水平。这清晰地证明了市场失灵：资源（劳动力）在生产中的配置不足。
| Market Structure | Wage | Employment |
| Perfect competition | W₁ (higher) | Q₁ (higher) |
| Monopsony | W₂ (lower) | Q₂ (lower) |
Monopsony outcome: W₂ < W₁ and Q₂ < Q₁
买方垄断结果：W₂ < W₁ 且 Q₂ < Q₁
5. Sources of Monopsony Power | 买方垄断力量的来源
Several factors can give rise to monopsony power in a labour market. One important source is geographical concentration: when firms are clustered in a remote location and workers face high mobility costs, the firm becomes the dominant employer. For example, a large hospital in a rural town may be the only major employer of nurses and healthcare assistants, giving it considerable wage-setting power.
多种因素可以在劳动力市场中产生买方垄断力量。一个重要来源是地理集中：当企业集中在偏远地区且工人面临高迁移成本时，该企业就成为占主导地位的雇主。例如，乡村城镇中的一家大型医院可能是护士和护理助理唯一的重大雇主，这赋予其相当大的工资设定权。
A second source is skill specificity. When workers possess highly specialised skills that are only valuable to one or two firms in the economy, their outside options are limited. Professional sports leagues, where players can negotiate only with a handful of team owners, illustrate this phenomenon. A third source is occupational licensing or professional barriers that restrict the mobility of workers between jobs and regions, further strengthening the employer’s bargaining position.
第二个来源是技能的专业性。当工人拥有高度专业化的技能，而这些技能只对经济中的一两家企业有价值时，他们的外部选择就受到限制。职业体育联盟中球员只能与寥寥数位球队老板谈判，就说明了这一现象。第三个来源是职业许可或专业壁垒，限制了工人跨职业和跨地区的流动性，进一步增强了雇主的议价地位。
A fourth factor is the absence of trade unions. In many countries, union membership has declined over recent decades, and where workers are not collectively organised, a dominant employer can exercise greater power over pay. Finally, asymmetric information plays a role: workers may be imperfectly informed about alternative job opportunities, wages and conditions elsewhere, reducing their ability to bargain effectively and strengthening the employer’s monopsonistic position.
第四个因素是工会的缺失。在许多国家，近几十年来工会会员人数有所下降，而在工人没有集体组织起来的地方，占主导地位的雇主可以行使更大的工资决定权。最后，信息不对称也起作用：工人可能对其他地方的其他工作机会、工资和条件了解不充分，削弱了他们有效谈判的能力，从而加强了雇主的买方垄断地位。
6. Wage Exploitation of Workers | 对工人的工资剥削
Wage exploitation in the monopsony model does not imply that the employer behaves unfairly or illegally; it refers to a systematic divergence between the wage paid and the marginal revenue product. The gap between MRP and the wage measures the degree of exploitation. Because the monopsonist pays all workers the same wage, the last worker hired receives less than the value of their own marginal product.
买方垄断模型中的工资剥削并不意味着雇主行为不公平或违法；它指的是所支付工资与边际收益产品之间的系统性差距。MRP 与工资之间的差距衡量了剥削程度。由于买方垄断者向所有工人支付相同的工资，最后一位被雇佣的工人所得的报酬低于其自身边际产品的价值。
This exploitation has several consequences for workers. Real wages are lower than they would be in a competitive market, meaning that workers receive a smaller share of the value they create. Lower wages reduce the standard of living and can discourage labour supply over the long run. The underpayment of labour may also cause skills shortages, as workers choose to train for professions where their productivity—and therefore remuneration—is more fairly compensated.
这种剥削对工人产生了若干后果。实际工资低于竞争市场上的水平，意味着工人从他们所创造的价值中获得较小的份额。较低的工资降低了生活水平，并且从长期来看会抑制劳动力供给。对劳动力支付不足还可能导致技能短缺，因为工人会选择接受那些生产率——因此报酬——得到更公平补偿的职业培训。
Moreover, the reduction in employment under monopsony creates a welfare loss. Workers who would be willing to work at the competitive wage are excluded from employment, generating a deadweight loss in the labour market. This represents a misallocation of resources: the economy fails to produce the maximum possible output from its available labour endowment because the monopsonist restricts hiring to hold down wages.
此外，买方垄断下的就业减少造成了福利损失。那些愿意在竞争性工资水平下工作的工人被排除在就业之外，在劳动力市场产生了无谓损失。这代表资源的错配：经济体未能利用其可用劳动力禀赋生产尽可能最大的产出，因为买方垄断者为了压低工资而限制雇佣。
7. Profit Implications for the Firm | 对企业的利润影响
While monopsony harms workers, it clearly benefits the employer in the form of higher profit. By paying workers less than their MRP, the firm captures a portion of the surplus that would otherwise accrue to labour. In the short run, the monopsonist enjoys abnormally high profits, which may be reinvested in capital equipment, research and development, or distributed to shareholders.
虽然买方垄断损害了工人，但它以更高利润的形式明显使雇主受益。通过支付给工人低于其 MRP 的工资，企业占有了本应归于劳动的那部分剩余。在短期内，买方垄断者享有超额利润，这些利润可能会再投资于资本设备、研发或分配给股东。
However, the long-run profit position is more nuanced. The low wages offered by a monopsonist can lead to high labour turnover, low morale and reduced effort, all of which raise the effective cost of labour. Workers may also invest less in firm-specific human capital, knowing that their employer does not share the gains of productivity growth fairly. In some cases, the monopsonist’s profit advantage is eroded by these inefficiencies, meaning the firm does not necessarily enjoy a sustainable competitive advantage.
然而，长期利润状况更为复杂。买方垄断者提供的低工资可能导致高员工流动率、低士气和工作积极性下降，这些都会提高劳动力的有效成本。工人也可能减少对企业特定人力资本的投资，因为他们知道雇主不会公平分享生产率增长的收益。在某些情况下，买方垄断者的利润优势会被这些低效率所侵蚀，这意味着企业不一定享有可持续的竞争优势。
Furthermore, if the monopsonist faces competition in the product market, its ability to pass on higher labour costs is limited. But if the firm is also a monopolist in the product market, the combination of monopoly and monopsony power can lead to substantial profit accumulation, often at the expense of both workers and consumers. This ‘double marginalisation’ of surplus transfer is a key concern for competition policy.
此外，如果买方垄断者在产品市场上面临竞争，其转嫁更高劳动力成本的能力就受到限制。但如果企业在产品市场同时又是垄断者，垄断与买方垄断力量的结合可能导致可观的利润积累，且往往以工人和消费者为代价。这种剩余转移的“双重边际化”是竞争政策关注的关键问题。
8. Minimum Wage in a Monopsony Market | 买方垄断市场中的最低工资
One of the most counterintuitive results in A-Level Economics is the effect of a minimum wage in a monopsony market. In a perfectly competitive labour market, a minimum wage set above the equilibrium wage causes unemployment, as the quantity of labour supplied exceeds the quantity demanded. However, in a monopsony market, the introduction of a carefully set minimum wage can actually increase both wages and employment.
A-Level 经济学中最反直觉的结果之一是买方垄断市场中最低工资的影响。在完全竞争的劳动力市场中，设定在均衡工资之上的最低工资会导致失业，因为劳动力供给量超过需求量。然而，在买方垄断市场中，引入设置得当的最低工资实际上可以增加工资和就业。
The reasoning is straightforward. When the minimum wage is set between the monopsony wage (W₂) and the competitive wage (W₁), the firm faces a horizontal labour supply curve at the minimum wage, provided it wishes to hire no more workers than are willing to supply at that wage. The marginal cost of labour becomes constant (equal to the minimum wage) rather than rising, removing the incentive to restrict employment. As a result, the firm hires more workers, moving closer to the competitive equilibrium.
其推理非常简单。当最低工资设定在买方垄断工资（W₂）和竞争性工资（W₁）之间时，只要企业希望雇佣的人数不超过在该工资水平下愿意工作的工人数量，企业就面临一条在最低工资处的水平劳动力供给曲线。劳动力的边际成本变为常数（等于最低工资），而不是上升，从而消除了限制就业的激励。结果，企业雇佣更多工人，向竞争性均衡靠近。
Minimum wage Wₘ such that W₂ < Wₘ ≤ W₁ increases employment
最低工资 Wₘ 满足 W₂ < Wₘ ≤ W₁ 时，就业增加
If the minimum wage is set too high above W₁, however, the market reverts to the competitive outcome and then to standard unemployment effects. The efficacy of a minimum wage therefore depends critically on its level relative to the competitive wage. This result provides an important theoretical justification for minimum wage legislation, but it must be applied with caution: measuring the competitive wage in practice is difficult, and setting the wage floor too high carries real risks.
然而，如果最低工资定得远高于 W₁，市场就会恢复到竞争性结果，然后出现标准的失业效应。因此，最低工资的有效性关键取决于其相对于竞争性工资的水平。这一结果为最低工资立法提供了重要的理论依据，但必须谨慎应用：在实践中衡量竞争性工资是困难的，而且将工资下限设定过高会带来真实的风险。
9. Trade Unions as a Countervailing Force | 工会作为制衡力量
Trade unions can act as a countervailing force to monopsony power. By organising workers collectively, unions can negotiate for a higher wage and better conditions, effectively shifting the wage outcome upward along to the monopsonist’s MRP schedule. In the standard model, a union that successfully negotiates a wage above W₂ will raise both wages and employment, as the firm responds to the new, higher marginal cost of labour by hiring more workers at the wage floor.
工会可以作为买方垄断力量的制衡力量。通过将工人集体组织起来，工会可以谈判争取更高的工资和更好的条件，有效地将工资结果沿着买方垄断者的 MRP 曲线向上推移。在标准模型中，成功谈判高于 W₂ 的工资的工会将同时提高工资和就业，因为企业会以新的、更高的劳动力边际成本回应，在工资下限处雇佣更多工人。
Unions also reduce the information asymmetry that workers face. Through collective bargaining, unions can gather and disseminate information about wages in other firms and regions, improving workers’ ability to make informed decisions about where to work. This increases the effective labour supply elasticity facing the employer and weakens monopsonistic exploitation.
工会还减少了工人面临的信息不对称。通过集体谈判，工会可以收集和传播有关其他企业和地区工资的信息，改善工人做出就业决策的能力。这增加了雇主面临的劳动力供给弹性，削弱了买方垄断剥削。
Nevertheless, the effect of unions is not always positive. If a union sets the wage too high—above the competitive equilibrium—the result may be job losses among the very workers the union seeks to protect. Moreover, insider-outsider problems can arise, where employed union members (insiders) secure high wages at the expense of the unemployed or non-members (outsiders). Whether unions improve labour market outcomes therefore depends on the bargaining structure and the level at which wages are set.
然而，工会的影响并不总是积极的。如果工会将工资设定过高——高于竞争性均衡——结果可能是工会想要保护的工人失业。此外，还可能产生内部人—外部人问题（insider-outsider problem），即已就业的工会成员（内部人）以失业者或非会员（外部人）为代价获得高工资。因此，工会能否改善劳动力市场结果取决于谈判结构和工资设定水平。
10. Evaluation of Monopsony Analysis | 对买方垄断分析的评估
While the monopsony model is a powerful analytical tool, its real-world applicability must be evaluated critically. In practice, pure monopsony—where only one employer exists—is rare. More common is oligopsony, where a few large firms dominate the market, or monopsonistic competition, where many employers exist but each faces a somewhat upward-sloping labour supply curve due to differentiation (e.g., working conditions, location, or non-pay benefits).
尽管买方垄断模型是一个强大的分析工具，但其现实适用性必须加以批判性评估。在实践中，纯粹的买方垄断——只有一个雇主存在——很少见。更常见的是寡头买方垄断（oligopsony），即少数大型企业主导市场；或者买方垄断竞争（monopsonistic competition），即存在许多雇主，但每个雇主都面临一条略显向上倾斜的劳动力供给曲线，这是因为存在差异化（例如工作条件、地理位置或非工资福利）。
The existence of a wide range of ‘frictions’ in labour markets—search costs, mobility costs, job-specific training and imperfect information—means that even apparently competitive markets exhibit some degree of monopsony-like power. Extensive empirical research using natural experiments, such as the introduction of minimum wages in various countries, has found little evidence of the employment losses predicted by the competitive model, suggesting that monopsony power is more widespread than traditionally assumed.
劳动力市场中存在各种各样的“摩擦”——搜索成本、迁移成本、工作特定培训和信息不完善——意味着即使表面上竞争的市场也表现出某种程度的类买方垄断权力。利用自然实验（例如各国引入最低工资）的大量实证研究发现，几乎没有证据表明竞争性模型所预测的就业损失，这表明买方垄断权力比传统假设更为普遍。
Another limitation of the model is its static nature. The monopsony model focuses on a single-period equilibrium and ignores dynamic factors such as training, innovation and productivity growth. A monopsonist that invests in worker training may generate productivity gains that offset its wage-saving behaviour. Conversely, a monopsonist that simply pays low wages may attract low-quality workers, creating adverse selection and reducing the quality of the firm’s workforce and output.
该模型的另一个局限是其静态性质。买方垄断模型侧重于单期均衡，忽略了培训、创新和生产率增长等动态因素。投资于工人培训的买方垄断者可能产生生产率的增长，从而抵消其节省工资的行为。相反，仅仅支付低工资的买方垄断者可能吸引低质量的工人，产生逆向选择，降低企业劳动力和产出的质量。
Finally, the model’s policy implications depend on the counterfactual. If the alternative to a single dominant employer is genuinely a competitive market, then intervention to break up monopsony power is justified. But if the alternative is no employment at all—as might be the case for a factory town with high transportation costs—then the monopsonist may be providing a net social benefit, even while earning economic rent from its position.
最后，该模型的政策含义取决于反事实的情况。如果替代单一主导雇主的方案真的是一个竞争性市场，那么干预以打破买方垄断权力就是合理的。但如果替代方案是完全没有就业——比如一个交通成本很高的工厂城镇可能就是这种情况——那么买方垄断者可能正在提供净社会收益，即使它从中获得了经济租金。
11. Conclusion | 结论
The monopsony model provides a rich and nuanced understanding of how labour markets operate when employers possess market power. By hiring fewer workers and paying lower wages than a competitive market, the monopsonist exploits the gap between the marginal cost of labour and the marginal revenue product, generating profits at the expense of workers and creating a deadweight loss for society at large.
买方垄断模型为理解当雇主拥有市场力量时劳动力市场的运作方式提供了丰富而细致的视角。通过比竞争市场雇佣更少的工人和支付更低的工资，买方垄断者利用了劳动力边际成本与边际收益产品之间的差距，以牺牲工人利益为代价获取利润，并给整个社会带来无谓损失。
The model also yields powerful policy insights. A minimum wage set at the appropriate level can simultaneously raise wages and employment—a conclusion that directly challenges the traditional competitive-market prediction. Trade unions, when they act responsibly, can also counterbalance employer power. However, the model must be applied with care, as its assumptions seldom hold in their pure form in the real world.
该模型还产生了强有力的政策启示。设定在适当水平的最低工资可以同时提高工资和就业——这一结论直接挑战了传统竞争性市场的预测。工会如果负责任地行事，也可以制衡雇主的权力。然而，在使用该模型时必须谨慎，因为其假设在现实世界中很少以纯粹的形式成立。
For CIE A-Level students, mastering the monopsony model is essential not only for examination purposes but also for developing a critical understanding of contemporary labour-market debates, including the living wage campaign, the gig economy and the regulation of dominant tech and healthcare employers. The ability to evaluate, apply and criticise the model with real-world examples is exactly what distinguishes top-grade answers in both structured essays and data-response questions.
对于 CIE A-Level 学生来说，掌握买方垄断模型不仅对考试至关重要，而且对于培养对当代劳动力市场辩论的批判性理解也是必需的，这些辩论包括生活工资运动、零工经济以及对占主导地位的科技和医疗保健雇主的监管。能够运用现实世界的例子来评估、应用和批判该模型，正是高分段在结构化论文和数据分析题中脱颖而出的关键。
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