📚 Year 12 CCEA Economics: Case Study Practice Drills | CCEA AS经济学：案例研究实战演练
In CCEA AS Economics, case study questions test your ability to apply economic concepts to real-world scenarios. This article provides a structured set of drills designed around typical Year 12 topics, helping you master analysis, evaluation and diagrammatic skills.
在CCEA AS经济学中，案例研究题目考查你将经济学概念应用于真实情境的能力。本文围绕典型的Year 12课题提供了一套结构化演练，帮助你掌握分析、评估和图示技巧。
1. The Case Study Method | 案例研究法
Always begin by identifying the key economic principles involved, such as demand, supply, elasticity, market failure or macroeconomic objectives. Read the extract carefully and underline trigger words like 'tax', 'subsidy', 'recession' or 'external cost'.
始终从识别所涉及的关键经济学原理开始，例如需求、供给、弹性、市场失灵或宏观经济目标。仔细阅读材料，并划出如“税收”、“补贴”、“衰退”或“外部成本”等触发词。
Next, draw relevant diagrams. For micro cases, use supply and demand diagrams showing shifts, price controls or tax incidence. For macro cases, use AD/AS diagrams or Phillips curve representations. Label everything clearly.
接下来，绘制相关图表。对于微观案例，使用供需图展示变动、价格控制或税收负担。对于宏观案例，使用AD/AS图或菲利普斯曲线图。清楚地标注所有内容。
Evaluation is essential. Consider the magnitude of changes, time lags, unintended consequences and the role of elasticity. A strong answer always weighs both sides before reaching a reasoned conclusion.
评估至关重要。考虑变化的幅度、时滞、意外后果以及弹性的作用。高分的答案总是在得出结论前权衡正反两面。
2. Drill 1: A Coffee Supply Shock | 演练1：咖啡供应冲击
Scenario: A severe drought in Brazil destroys 30% of the coffee harvest. At the same time, consumer incomes rise in major importing countries. Using demand and supply analysis, explain the likely impact on the equilibrium price and quantity of coffee.
情景：巴西一场严重干旱摧毁了30%的咖啡收成。同时，主要进口国的消费者收入上升。运用供需分析，解释对咖啡均衡价格和数量的可能影响。
Step 1: Draw a supply curve shifting left due to the drought, raising price and lowering quantity. Step 2: Draw a demand curve shifting right because coffee is a normal good, which further raises price but offsets some quantity reduction.
第一步：画出供给曲线因干旱向左移动，价格上升数量下降。第二步：由于咖啡是正常品，需求曲线向右移动，这进一步推高价格但部分抵消了数量的下降。
Evaluation: The final outcome depends on the relative magnitudes of the shifts. If the increase in demand is larger than the supply reduction, quantity may actually rise. The price will unambiguously increase. Mention the role of price elasticity of demand for coffee – if demand is inelastic, the price rise will be sharper.
评估：最终结果取决于变动幅度的大小。若需求增加大于供给减少，数量实际上可能上升。价格将明确上涨。提到咖啡需求价格弹性的作用——如果需求缺乏弹性，价格上涨将更剧烈。
3. Drill 2: Sugar Tax and Elasticity | 演练2：糖税与弹性
Scenario: The UK introduced a Soft Drinks Industry Levy in 2018. Evaluate how the price elasticity of demand for sugary drinks affects the effectiveness of this tax in reducing consumption and raising government revenue.
情景：英国于2018年引入软饮料行业税。评估含糖饮料的需求价格弹性如何影响该税在减少消费和增加政府收入方面的有效性。
Definition and data: Price elasticity of demand (PED) measures responsiveness of quantity demanded to a price change. Studies suggest PED for sugary drinks is around –0.8 to –1.2, meaning relatively inelastic to unit elastic.
定义和数据：需求价格弹性（PED）衡量需求量对价格变化的反应程度。研究表明含糖饮料的PED约为–0.8至–1.2，即相对缺乏弹性到单位弹性。
Analysis: With an inelastic demand, a tax that raises the price leads to a proportionally smaller fall in quantity demanded, so consumption reduction is modest. However, government revenue rises significantly because the tax is collected on a large volume of sales. If demand were more elastic, the health outcome would improve more but revenue would be lower.
分析：在缺乏弹性需求下，提高价格的税收导致需求量下降比例较小，因此消费减少有限。然而，政府收入显著增加，因为税收课征于大量销售。若需求更具弹性，健康结果改善更大，但收入会更低。
Evaluation: The tax may encourage producers to reformulate drinks to avoid the levy, shifting supply. Also consider regressive effects and cross-elasticity with diet drinks. These factors make the overall outcome more complex.
评估：税收可能促使生产商重新调配饮品以避免征税，从而移动供给。还要考虑累退效应以及与无糖饮料的交叉弹性。这些因素使得总体结果更为复杂。
4. Drill 3: Electric Vehicles and Positive Externalities | 演练3：电动汽车与正外部性
Scenario: Governments often subsidise electric vehicle (EV) purchases. Identify the market failure that justifies this intervention and illustrate with a diagram showing the external benefit.
情景：政府经常补贴电动汽车（EV）的购买。识别证明这一干预合理的市场失灵，并用显示外部收益的图表进行说明。
The market failure is a positive externality from consumption. When a consumer buys an EV, they reduce air pollution and carbon emissions, benefiting third parties. The private benefit is lower than the social benefit, leading to under-consumption at the free market equilibrium Qe rather than Qopt.
市场失灵是消费的正外部性。消费者购买电动汽车时，减少了空气污染和碳排放，使第三方受益。私人收益低于社会收益，导致自由市场均衡数量Qe低于社会最优数量Qopt。
Draw a marginal private benefit (MPB) curve and a higher marginal social benefit (MSB) curve. The subsidy shifts MPB rightwards to align with MSB, increasing quantity to Qopt and internalising the externality.
绘制一条边际私人收益(MPB)曲线和一条更高的边际社会收益(MSB)曲线。补贴使MPB向右移动以使与MSB对齐，将数量提升至Qopt并内化外部性。
Evaluation: The size of the subsidy must cover the external benefit per unit. However, if EVs remain expensive, the subsidy may disproportionately benefit higher-income groups. Also, the environmental gain depends on how electricity is generated; if fossil fuels dominate the grid, the net external benefit is smaller.
评估：补贴的规模必须覆盖每单位的外部收益。然而，如果电动汽车仍然昂贵，补贴可能不成比例地惠及高收入群体。此外，环境收益取决于电力的来源；若化石燃料主导电网，净外部收益较小。
5. Drill 4: Rent Controls and Government Failure | 演练4：租金管制与政府失灵
Scenario: A city imposes a maximum rent below the equilibrium to make housing affordable. Analyse the likely outcomes and explain why this may represent government failure.
情景：某城市实施低于均衡水平的最高租金以使住房可负担。分析可能的结果并解释为何这可能代表政府失灵。
A price ceiling set below equilibrium creates excess demand (a shortage). Landlords reduce supply or neglect maintenance. Black markets may emerge. The policy hurts some of the very people it intends to help, as they cannot find rental properties.
设定在均衡水平以下的价格上限会产生超额需求（短缺）。房东减少供给或忽视维修。黑市可能出现。该政策伤害了一些它本想帮助的人，因为他们找不到租赁物业。
Government failure occurs because the intervention leads to a net welfare loss: consumer surplus gains are offset by producer surplus losses and deadweight loss from the shortage. Additionally, administrative costs and misallocation of resources worsen efficiency.
政府失灵的发生是因为干预导致了净福利损失：消费者剩余的增加被生产者剩余的损失和短缺造成的无谓损失所抵消。此外，行政成本和资源配置不当加剧了效率低下。
Evaluation: Some tenants benefit from lower rents, so the policy is not a total failure. But over time, reduced investment in housing stock reduces quality and quantity, creating long-term problems. Alternative policies like housing vouchers might be more efficient.
评估：一些租户从较低租金中受益，因此该政策并非完全失败。但随着时间的推移，住房存量投资减少降低了质量和数量，造成长期问题。像住房券这样的替代政策可能更有效率。
6. Drill 5: Interpreting GDP and Inflation Data | 演练5：解读GDP与通胀数据
Scenario: Country X reports real GDP growth of 2.5%, CPI inflation of 4.2% and unemployment rate of 6.8%. Assess the state of the economy and suggest possible causes.
情景：X国报告实际GDP增长2.5%，CPI通胀4.2%，失业率6.8%。评估经济状况并提出可能的原因。
Moderate growth with above-target inflation suggests an economy in an upswing but facing supply-side constraints or demand-pull pressures. The unemployment rate is relatively high for this growth rate, indicating possible structural unemployment or labour market rigidities.
温和增长伴随超出目标的通胀，表明经济处于上升期但面临供给侧制约或需求拉动压力。相对于此增长率，失业率较高，表明可能存在结构性失业或劳动力市场僵化。
Causes: Demand-pull inflation from strong consumer spending could coexist with cost-push inflation from rising energy prices. High unemployment despite growth may reflect a mismatch of skills (structural) or inadequate aggregate demand. Use a Phillips curve to show the trade-off: rising inflation often coincides with falling unemployment, but this relationship may break down due to supply shocks.
原因：强劲消费支出导致的需求拉动通胀可能与能源价格上涨导致的成本推动通胀并存。尽管有增长但高失业率可能反映技能错配（结构性）或总需求不足。用菲利普斯曲线展示权衡：通胀上升通常与失业下降同时发生，但这一关系可能因供给冲击而瓦解。
Evaluation: The government might consider contractionary monetary policy to curb inflation, but this could harm growth and raise unemployment. Careful judgement is needed, supported by further data on capacity utilisation and wage growth.
评估：政府可能考虑紧缩性货币政策以遏制通胀，但这可能危害增长并提高失业率。需谨慎判断，并以产能利用率和工资增长的进一步数据为支撑。
7. Drill 6: An Expansionary Fiscal Policy | 演练6：扩张性财政政策
Scenario: To combat a recession, the government increases infrastructure spending by £20 billion and cuts income tax. Illustrate the effect on aggregate demand and evaluate potential drawbacks.
情景：为对抗经济衰退，政府增加200亿英镑基础设施支出并削减所得税。说明对总需求的影响并评估潜在缺点。
Both measures boost aggregate demand (AD). Higher government spending directly increases AD; tax cuts raise disposable income, boosting consumption. AD shifts right, increasing real GDP and possibly reducing unemployment.
两项措施均刺激总需求(AD)。政府支出增加直接提高AD；减税增加可支配收入，刺激消费。AD右移，提高实际GDP并可能降低失业率。
Short-term effects depend on the multiplier. If
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