📚 Wage Determination in Imperfect Markets | 不完全市场中的工资决定
In competitive labour markets, wages are set by the interaction of supply and demand, with no individual buyer or seller able to influence the wage rate. However, in imperfect markets, employers or workers may possess market power, leading to wages and employment levels that differ from the competitive equilibrium.
在完全竞争的劳动力市场中，工资由供求相互作用决定，任何单个买方或卖方都无法影响工资率。然而，在不完全市场中，雇主或工人可能拥有市场势力，导致工资和就业水平偏离竞争性均衡。
1. From Perfect to Imperfect Labour Markets | 从完全劳动力市场到不完全劳动力市场
In a perfectly competitive labour market, firms are wage takers: they can hire as many workers as they want at the going market wage, so the supply of labour to an individual firm is perfectly elastic. The equilibrium wage equals the marginal revenue product of labour (MRP_L) and the marginal cost of labour (MCL).
在完全竞争的劳动力市场中，企业是工资接受者：它们可以按现行市场工资雇佣任意数量的工人，因此单个企业面临的劳动供给曲线是完全弹性的。均衡工资等于劳动的边际收益产品（MRP_L）和劳动边际成本（MCL）。
Imperfect markets arise when either buyers (employers) or sellers (workers) have enough market power to influence the wage. Key cases include monopsony, trade union monopoly, bilateral monopoly, efficiency wages, and asymmetric information.
当买方（雇主）或卖方（工人）拥有足够影响工资的市场势力时，就出现不完全市场。主要情形包括买方垄断、工会垄断、双边垄断、效率工资和信息不对称。
2. Monopsony Power in Labour Markets | 劳动力市场中的买方垄断力量
A monopsony exists when there is a single buyer of labour or a dominant employer in a local labour market. Because the firm faces the market supply curve of labour, which is upward sloping, it must pay a higher wage to attract additional workers. This means the marginal cost of labour (MCL) exceeds the average cost of labour (ACL), which is the wage rate.
当劳动力市场只有一个买方或一个占主导地位的雇主时，就存在买方垄断。由于企业面临向上倾斜的市场劳动供给曲线，它必须支付更高工资来吸引额外工人。这意味着劳动边际成本（MCL）高于劳动平均成本（ACL），即工资率。
MCL = W + L × ΔW/ΔL > W = ACL
A profit-maximising monopsonist hires workers up to the point where MRP_L equals MCL, not where MRP_L equals W. At this level, the wage paid is found from the labour supply curve. Both employment and the wage are lower than in a competitive labour market, creating deadweight loss and exploitation of workers.
追求利润最大化的买方垄断者雇佣工人直到 MRP_L 等于 MCL，而不是 MRP_L 等于工资 W。在这一劳动数量下，实际支付的工资从劳动供给曲线上读取。就业和工资都低于竞争性劳动力市场，造成无谓损失和对工人的剥削。
3. Diagram Analysis of Monopsony | 买方垄断的图形分析
Draw the upward-sloping labour supply curve (ACL) and the steeper MCL curve above it. The downward-sloping MRP_L curve intersects MCL at the monopsony employment level Lm. The wage Wm is read off the ACL curve at Lm. If the market were competitive, equilibrium would be where MRP_L intersects ACL, giving Lc and Wc.
画出向上倾斜的劳动供给曲线（ACL）和在其上方的更陡峭的 MCL 曲线。向下倾斜的 MRP_L 曲线与 MCL 相交于买方垄断就业量 Lm。工资 Wm 从 ACL 曲线上对应 Lm 的点读出。如果市场是竞争性的，均衡将在 MRP_L 与 ACL 相交处，得到 Lc 和 Wc。
Thus Lm < Lc and Wm < Wc. The shaded area between MCL and ACL, bounded by employment, represents the monopsonist’s exploitation of workers, while the triangle between MRP_L and ACL from Lm to Lc shows the deadweight welfare loss.
因此 Lm < Lc 且 Wm < Wc。MCL 与 ACL 之间由就业量围成的阴影区域代表买方垄断者对工人的剥削，而 MRP_L 与 ACL 之间从 Lm 到 Lc 的三角形区域表示无谓福利损失。
4. Trade Union Power and Wage Bargaining | 工会力量与工资谈判
On the supply side, trade unions can act as a monopoly seller of labour, using collective bargaining to push wages above the competitive level. A union may restrict labour supply through entry requirements, training barriers, or strike action, shifting the supply curve left or setting a minimum acceptable wage.
在供给方面，工会可以充当劳动的垄断卖方，通过集体谈判将工资推高到竞争水平之上。工会可能通过准入要求、培训壁垒或罢工行动来限制劳动供给，使供给曲线左移或设定最低可接受工资。
If a union successfully raises the wage above equilibrium, the quantity of labour demanded falls, creating unemployment among union members unless labour demand is inelastic. The union faces a trade-off between higher wages and lower employment.
如果工会成功将工资提高到均衡水平之上，劳动需求量会下降，从而在工会成员中造成失业，除非劳动需求弹性较小。工会面临更高工资与更低就业之间的权衡。
5. Bilateral Monopoly | 双边垄断
A bilateral monopoly occurs when a single buyer (monopsonist) faces a single seller (trade union). In this case, the wage rate is not determined purely by market forces; it depends on the relative bargaining power and negotiation skills of both sides. The outcome can lie anywhere between the monopsony wage and the union’s target wage.
当单一买方（买方垄断者）面对单一卖方（工会）时，就出现双边垄断。在这种情况下，工资率并非纯粹由市场力量决定，而是取决于双方的相对谈判力和谈判技巧。结果可能位于买方垄断工资与工会目标工资之间的任何位置。
Economic theory cannot predict a unique equilibrium wage in bilateral monopoly; it establishes a range. Factors such as union density, public support, firm profitability, and strike funds influence the final settlement.
经济理论无法预测双边垄断中的唯一均衡工资；它只能确定一个区间。工会密度、公众支持、企业盈利能力以及罢工基金等因素会影响最终协议。
6. Efficiency Wage Theory | 效率工资理论
Efficiency wage theory explains why firms in imperfect markets may voluntarily pay wages above the market-clearing level. Higher wages can raise worker productivity by reducing shirking, lowering labour turnover, attracting higher-quality applicants, and improving morale. The firm sets the wage where the marginal benefit of a higher wage equals its marginal cost.
效率工资理论解释了为什么不完全市场中的企业可能自愿支付高于市场出清水平的工资。较高的工资可以通过减少偷懒、降低劳动力流失、吸引更高质量的求职者以及提高士气来提升劳动生产率。企业将工资设定在更高工资的边际收益等于其边际成本的水平。
This creates a wage above the competitive equilibrium and may result in persistent unemployment, as the efficiency wage exceeds the wage at which labour supply equals labour demand.
这将导致工资高于竞争性均衡，并可能产生持续性失业，因为效率工资超过了劳动供给等于劳动需求的工资水平。
7. Minimum Wage in Imperfect Markets | 不完全市场中的最低工资
In a competitive labour market, a minimum wage above equilibrium reduces employment. However, in a monopsonistic labour market, a carefully set minimum wage can increase both wages and employment. Because the minimum wage becomes the new marginal cost of labour up to a certain employment level, the monopsonist no longer needs to raise wages to attract extra workers; MCL becomes horizontal at the minimum wage until it meets the supply curve.
在竞争性劳动力市场中，高于均衡水平的最低工资会减少就业。然而，在买方垄断的劳动力市场中，设置得当的最低工资可以同时提高工资和就业。由于最低工资成为新的劳动边际成本（直到某一就业水平），买方垄断者不再需要提高工资来吸引额外工人；MCL 在最低工资处变为水平线，直到与供给曲线相交。
Employment may rise from Lm towards Lc if the minimum wage is set between the monopsony wage and the competitive wage. If set too high (above the competitive wage), employment will fall, as in a competitive market.
如果最低工资设定在买方垄断工资与竞争性工资之间，就业量可能从 Lm 向 Lc 增加。如果设定过高（高于竞争性工资），就业量将会下降，就像在竞争性市场中一样。
8. Discrimination and Imperfect Information | 歧视与不完全信息
Imperfect labour markets also feature wage differentials caused by discrimination, segmented labour markets, and incomplete information. Employers may pay different wages to equally productive workers based on gender, ethnicity, or age, either due to prejudice or statistical discrimination. Information asymmetries make it costly for workers to search for better jobs, giving employers some monopsony power.
不完全劳动力市场还存在由歧视、分割的劳动力市场和不完全信息引起的工资差异。雇主可能基于性别、种族或年龄，对生产率相同的工人支付不同工资，原因可能是偏见或统计性歧视。信息不对称使工人寻找更好工作的成本较高，从而赋予雇主一定的买方垄断力量。
These imperfections can persist even without formal barriers, as social norms, networks, and unequal access to training reinforce wage gaps.
即使没有正式壁垒，这些不完全性也可能持续存在，因为社会规范、关系网络以及培训机会的不平等会强化工资差距。
9. Evaluation and Policy Implications | 评价与政策含义
When evaluating wage determination in imperfect markets, consider both efficiency and equity. Monopsony power leads to lower wages and employment, so policies such as minimum wages, competition policy, and improved labour mobility can reduce inefficiency. Trade union power may raise wages but can cause unemployment; the net effect depends on labour demand elasticity and productivity effects.
在评价不完全市场中的工资决定时，需要同时考虑效率与公平。买方垄断力量导致更低的工资和就业，因此最低工资、竞争政策和改善劳动力流动性等政策可以减少无效率。工会力量可能提高工资，但可能导致失业；净效应取决于劳动需求弹性和生产率效应。
Some interventions, such as training and reducing information asymmetries, can raise both efficiency and equity. However, policy makers must be cautious: a minimum wage set too high in a competitive or weakly monopsonistic market can reduce employment.
一些干预措施，如培训和减少信息不对称，可以同时提高效率和公平。然而，政策制定者必须谨慎：在竞争性或弱买方垄断的市场中，最低工资设定过高可能减少就业。
10. Exam Focus: Key Diagrams and Definitions | 考试重点：关键图表与定义
For Cambridge A-Level Economics, make sure you can draw and label the monopsony diagram, showing ACL, MCL, MRP_L, Lm, Wm, Lc, Wc, and the welfare loss. Define monopsony, marginal cost of labour, bilateral monopoly, efficiency wages, and explain the minimum wage result under monopsony.
对于剑桥 A-Level 经济学，务必能够绘制并标注买方垄断图，显示 ACL、MCL、MRP_L、Lm、Wm、Lc、Wc 以及福利损失。定义买方垄断、劳动边际成本、双边垄断、效率工资，并解释买方垄断下最低工资的结果。
Common exam errors include confusing the MCL and ACL curves, forgetting that the wage is read off the supply curve, and assuming a minimum wage always reduces employment.
常见考试错误包括混淆 MCL 和 ACL 曲线、忘记工资应从供给曲线上读取，以及假设最低工资总是减少就业。
11. Conclusion | 总结
In imperfect labour markets, wages are determined by market power, institutional forces, and information problems rather than by competitive supply and demand alone. Monopsony depresses wages and employment below competitive levels, while trade unions and efficiency wages push wages above market-clearing levels, with mixed effects. Understanding these models is essential for evaluating real-world labour market policies.
在不完全劳动力市场中，工资由市场势力、制度力量和信息问题共同决定，而不仅仅由竞争性供求决定。买方垄断将工资和就业压低到竞争水平以下，而工会和效率工资将工资推高到市场出清水平以上，影响不一。理解这些模型对于评价现实世界的劳动力市场政策至关重要。
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