The Influence of trade unions in determining wages and levels of employment — AQA A-Level Economics

In AQA A-Level Economics, trade unions act as monopoly sellers of labour, exercising collective bargaining power to push wage rates above competitive equilibrium levels. While trade unions can cause classical real-wage unemployment in competitive labour markets, they can simultaneously increase both wages and employment when confronting a monopsonist employer.

This topic examines how trade unions act as collective bargaining agents to influence wage determination and employment levels across different labour market structures. Students explore the microeconomic mechanisms through which unions negotiate, including their impact in perfectly competitive markets versus monopsonistic markets.

Understanding trade unions is essential for assessing real-world wage inequality, collective bargaining legislation, public versus private sector pay disputes, and national minimum wage impacts. It links theoretical concepts of derived demand and Marginal Revenue Product with applied microeconomic policy and macroeconomic supply-side performance.

• →Trade Union as a Monopoly Seller of Labour: A union restricts labour supply or acts as a wage-setter, forcing employers to face a kinked or perfectly elastic labour supply curve at the union wage.
• →Bilateral Monopoly: The market condition where a trade union (monopoly seller) bargains directly with a monopsony employer (monopoly buyer), potentially resolving wage exploitation.
• →Marginal Revenue Product of Labour (MRPL): Demand for labour equals marginal physical product multiplied by price (MPP x P); union wage increases force firms to equate the new marginal cost of labour to MRPL.
• →Marshall's Rules of Derived Demand: Four conditions (substitutability of capital, PED of final product, labour cost proportion, elasticity of supply of alternative factors) that dictate how severely employment contracts following a wage rise.

• Explaining how high union density and strong member militancy increase collective bargaining power.
• Analysing the impact of the wage elasticity of labour demand; inelastic demand allows for wage increases with minimal job losses.
• Evaluating the threat of capital substitution (automation) as a factor that weakens a union's ability to demand higher wages.
• Assessing the role of government legislation, such as strike ballot thresholds, in restricting or enabling union influence.
• Discussing how the degree of product market competition affects the employer's ability to pass on higher wage costs to consumers.
• Explain that in a perfectly competitive labour market, a trade union negotiating a wage above equilibrium leads to a contraction in labour demand and an extension in labour supply.
• Identify that the introduction of a union in perfect competition results in higher wages but lower employment, creating classical unemployment.
• Explain that a monopsony employer restricts employment to keep wages low, operating where the marginal cost of labour equals the marginal revenue product.
• Analyse how a trade union in a monopsony creates a perfectly elastic labour supply curve up to the negotiated wage, equating the average and marginal cost of labour.
• Conclude that in a monopsony, a trade union can successfully negotiate higher wages whilst simultaneously increasing the level of employment.
• Accurately draw and label the axes: Wage rate on the y-axis and Quantity of labour on the x-axis.
• Illustrate the perfectly competitive market with intersecting labour supply and demand curves, and a horizontal union wage line above equilibrium.
• Clearly indicate the gap between labour supplied and labour demanded at the union wage to show unemployment in a competitive market.
• Draw a monopsony diagram featuring distinct average cost of labour and marginal cost of labour curves, alongside the marginal revenue product curve.
• Show the effect of a union in a monopsony by drawing a horizontal line at the negotiated wage, demonstrating the new kinked supply and marginal cost curves.

• 💡Use the concept of a bilateral monopoly (a trade union facing a monopsony employer) to evaluate how unions can successfully raise wages without reducing employment.
• 💡Apply the determinants of elasticity of labour demand (e.g., substitutability of capital, proportion of total costs) to explain why union power varies across different sectors.
• 💡Reference real-world examples, such as public sector strikes or the decline of manufacturing unions, to contextualise your arguments.
• 💡Always specify the initial market structure (perfect competition or monopsony) before analysing the impact of a trade union.
• 💡Use the concept of marginal revenue product to explain why employers reduce employment when unions raise wages in a competitive market.
• 💡Clearly distinguish between the average cost of labour (the supply curve) and the marginal cost of labour when discussing monopsony.
• 💡Practice drawing the monopsony trade union diagram repeatedly, as the kinked marginal cost curve is complex but highly rewarded.
• 💡Use a ruler and clear annotations to highlight the changes in wage and employment levels before and after union intervention.
• 💡Integrate your diagrammatic analysis directly into your written text, referring to specific points to support your arguments.
• 💡Always draw accurate diagrams showing both the Average Cost of Labour (ACL) and Marginal Cost of Labour (MCL) when evaluating union impacts in a monopsony context.
• 💡Ground your analysis in the elasticity of labour demand; explicitly state whether MRPL is elastic or inelastic before drawing conclusions about trade-offs between wage gains and employment losses.
• 💡In 25-mark essays, balance theoretical diagrams with UK context, noting the decline in trade union density since the 1980s and the growth of flexible and gig-economy labour markets.

• Assuming trade unions always cause unemployment; correction is to explain that in a monopsony market, a trade union can actually increase both wages and employment.
• Stating that unions have equal power in all industries; correction is to differentiate between markets, noting that highly skilled or public sector workers often have more inelastic demand and thus stronger unions.
• Ignoring the macroeconomic context; correction is to recognise that unions have less bargaining power during a recession when unemployment is high and replacement workers are readily available.
• Error: Assuming trade unions always cause unemployment. Correction: Explain that while unions cause unemployment in perfectly competitive markets, they can increase employment in a monopsony.
• Error: Confusing the marginal cost of labour with the average cost of labour in a monopsony. Correction: Remember that in a monopsony, the marginal cost of labour is higher than the average cost (supply) curve because the firm must raise wages for all workers to attract an additional worker.
• Error: Stating that unions shift the labour demand curve. Correction: Unions affect the labour supply curve by setting a wage floor, creating a kinked supply curve, rather than shifting the demand curve.
• Error: Forgetting to label the axes or curves correctly. Correction: Always label the y-axis as 'Wage rate' and the x-axis as 'Quantity of labour', and clearly label MRP, AC, and MC curves.
• Error: Drawing the marginal cost of labour curve below the average cost of labour curve in a monopsony. Correction: Ensure the marginal cost of labour curve is drawn above and steeper than the upward-sloping average cost of labour curve.
• Error: Failing to show the new employment level after union intervention in a monopsony. Correction: Clearly mark the new equilibrium where the horizontal section of the new marginal cost curve intersects the marginal revenue product curve.
• Trade unions always cause job losses when they raise wages. (Correction: This is only true in competitive labour markets. In a monopsony market, an appropriately set union wage can increase both the wage and the level of employment simultaneously.)
• Unemployment caused by a union wage is merely the number of workers fired. (Correction: Unemployment equals the total excess supply of labour (Qs - Qd) at the bargained wage, which includes both laid-off workers and new entrants drawn into the labour force by higher wages.)
• A union shifts the supply curve of labour parallel to the left. (Correction: A bargained wage introduces a perfectly elastic horizontal floor to the labour supply curve up to the original upward-sloping supply curve, creating a kink rather than a simple parallel shift.)

1. 1Day 1-2: Master the standard competitive labour market model and draw diagrams showing union mark-ups creating classical unemployment.
2. 2Day 3-4: Study monopsony labour markets; practice diagrammatic derivations of MCL being twice as steep as ACL, and identify the initial profit-maximising monopsony wage and employment levels.
3. 3Day 5-6: Overlay the union bargained wage onto the monopsony diagram (bilateral monopoly) to show how wages and employment can rise concurrently.
4. 4Day 7-8: Apply Marshall's rules of derived demand and review UK real-world examples (e.g., NHS unions, transport unions, minimum wage bodies) before tackling past paper 25-mark essay questions.

• 📋Diagrammatic 9-mark questions: Explain how the introduction of a trade union into a monopsony labour market affects wages and employment.
• 📋Data response 15-mark questions: Analyse the extent to which trade unions can protect real wages during periods of high inflation without worsening job security.
• 📋Essay 25-mark evaluation questions: Evaluate whether trade unions enhance economic welfare or act as a market failure in UK labour markets.