📚 Year 10 CAIE Economics: Case Study Practical Exercises | 10年级CAIE经济：案例分析实战演练
In the CAIE IGCSE Economics examination, Paper 2 often presents a structured case study followed by a series of questions that test your ability to apply economic concepts to real-world situations. This article walks you through a typical case study exercise, providing a hands-on method to sharpen your analytical writing and problem-solving skills. Mastering this approach is vital for achieving top marks.
在CAIE IGCSE经济学考试中，Paper 2通常会提供一个结构化的案例分析和一组后续问题，考查你把经济概念应用于实际情境的能力。本文将通过一个典型的案例练习，用实战方式帮你提升分析写作和问题解决技巧。掌握这种方法对获得高分至关重要。
1. The Case Study Scenario | 案例情景介绍
Let us consider a fictional but realistic scenario: Country X is a developing economy that heavily relies on imported smartphones. The government is proposing a 10% ad valorem tariff on smartphone imports. Its stated goals are to protect a new domestic assembly industry employing 5,000 workers and to reduce the trade deficit. Meanwhile, consumer advocacy groups warn that the tariff will push smartphones out of reach for many low-income households. At the same time, the government is subsidising mobile internet services to promote digital literacy and productivity. Research estimates suggest that the price elasticity of demand (PED) for smartphones in Country X is -0.8, and the cross-price elasticity of demand with mobile data plans is -0.5.
我们来考虑一个虚构但现实的情景：X国是一个发展中国家，严重依赖进口智能手机。政府提议对进口智能手机征收10%的从价关税。其宣称的目标是保护一个雇佣了5000名工人的新兴国内组装产业，并减少贸易逆差。与此同时，消费者权益组织警告说，关税会使许多低收入家庭买不起智能手机。同时，政府正在补贴移动互联网服务，以促进数字素养和生产力。研究估计，X国智能手机的需求价格弹性（PED）为-0.8，与移动数据套餐的交叉价格弹性为-0.5。
2. Identifying Core Economic Concepts | 识别核心经济概念
Before diving into analysis, you must identify the key concepts this case study touches upon: demand and supply, price elasticity of demand, indirect taxation (tariffs), subsidies, externalities, complementary goods, and government intervention. Always link each concept to the specific context of the case. For example, a tariff is a tax on imports that raises the domestic price and acts as a supply-side shock.
在深入分析之前，你必须先识别出案例所涉及的核心概念：需求与供给、需求价格弹性、间接税（关税）、补贴、外部性、互补品以及政府干预。始终要把每个概念和案例的具体情境联系起来。例如，关税是对进口商品征收的一种税，它会提高国内价格，并构成供给端的冲击。
3. Demand and Supply Analysis | 需求与供给分析
Smartphones are normal goods. Rising incomes in Country X would shift the demand curve to the right (D to D₁). Social trends, such as the growing need for mobile banking and social media, also boost demand. On the supply side, the market depends overwhelmingly on imports. The proposed tariff raises the cost of bringing phones into the country, causing the domestic supply curve to shift leftwards (S to S₁). The initial equilibrium price and quantity (P₀, Q₀) would move to a higher price (P₁) and a lower quantity (Q₁).
智能手机是正常商品。X国居民收入增加将使需求曲线向右移动（D到D₁）。移动银行和社交媒体日益增长的需求等社会趋势也会提振需求。在供给方面，市场严重依赖进口。拟议的关税提高了手机进入该国的成本，导致国内供给曲线向左移动（S到S₁）。初始均衡价格和数量（P₀, Q₀）将变为更高的价格（P₁）和更低的数量（Q₁）。
ternet services will also shift the demand for smartphones to the right. This reinforces the upward pressure on price, partially offsetting the contraction caused by the tariff. The net effect on equilibrium quantity depends on the relative strengths of these two policies, which you must evaluate.
由于智能手机和移动数据套餐是互补品（交叉价格弹性 = -0.5），对互联网服务的补贴也会使智能手机的需求曲线右移。这会加剧价格上升的压力，部分抵消关税造成的数量收缩。两种政策的相对力度将决定均衡数量的净效应，你必须对此进行评估。
4. Price Elasticity and Its Implications | 价格弹性及其影响
PED = %ΔQd / %ΔP = -0.8
martphones is price inelastic because the absolute value of PED is less than 1 (0.8). A 10% tariff that raises the price by, for example, 8% will cause quantity demanded to fall by only about 6.4% (0.8 × 8% small decrease in quantity imported means the trade deficit may not improve significantly.
智能手机的需求是缺乏价格弹性的，因为PED的绝对值小于1（0.8）。一项使价格上涨8%的10%关税，只会使需求量下降约6.4%（0.8 × 8%）。因此，智能手机的总支出将会上升，政府将获得可观的关税收入。然而，进口数量下降相对较小，意味着贸易逆差可能不会显著改善。
The inelastic demand also means consumers bear a larger share of the tariff burden than foreign producers. This has equity implications, especially since smartphones are increasingly essential for accessing services like education and healthcare. Low-income households will feel the price increase more acutely, which is the central argument of the consumer groups in the case.
缺乏弹性的需求还意味着消费者承担的关税负担比外国生产者更大。这产生了公平性问题，特别是因为智能手机对获取教育和医疗等服务日益重要。低收入家庭对价格上涨的感受会更深，这也是案例中消费者团体所持的核心论点。
5. Immediate Effects of the Tariff | 关税的直接影响
A 10% ad valorem tariff acts as an increase in the cost of supply for every imported unit. The domestic price rises from the world price (Pw) to Pw + tariff. The higher price encourages local assembly to expand, but given the infant industry's small scale, most demand will still be met by imports, now at a higher price.
10%的从价关税相当于每一进口单位的供给成本增加。国内价格从世界价格（Pw）上升到 Pw + 关税。较高的价格鼓励国内组装业扩张，但考虑到幼稚产业规模较小，大部分需求仍将由进口满足，只是价格更高。
We can illustrate the incidence of the tariff with a simple division of the tax burden:
| Stakeholder | Burden share |
| Consumers | Larger (demand inelastic) |
| Foreign producers | Smaller (they may lower pre-tariff price to stay competitive) |
| Government | Gains tariff revenue |
| Local assembly workers | Potential job gains |
我们可以用一个简单的税负划分表来说明关税的归宿：消费者承担较大份额（需求缺乏弹性），外国生产者承担较小份额（可能降低税前价格以保持竞争力），政府获得关税收入，本地组装工人可能获得就业增长。
6. Externalities and Market Failure | 外部性与市场失灵
Consuming and disposing of smartphones generates negative externalities: electronic waste, energy consumption during use, and resource depletion. In a free market, these external costs are ignored, leading to overconsumption. The tariff accidentally helps correct this by raising the price, reducing quantity towards the socially optimum level. However, a tariff is a blunt instrument because it does not directly target the externality source.
智能手机的消费和废弃会产生负外部性：电子垃圾、使用过程中的能源消耗以及资源枯竭。在自由市场中，这些外部成本被忽视，导致过度消费。关税通过提高价格、减少数量，无意中帮助将消费量推向社会最优水平。然而，关税是一种钝性工具，因为它没有直接针对外部性的源头。
Meanwhile, subsidising mobile internet creates positive externalities. Increased digital literacy can enhance productivity, improve access to information, and reduce transaction costs across the economy—benefits that go beyond individual users. This justifies government intervention on efficiency grounds.
与此同时，补贴移动互联网会产生正外部性。数字素养的提高可以提升生产力、改善信息获取并降低整个经济的交易成本——这些好处超出了个人用户的范围。这从效率角度为政府干预提供了理由。
7. The Subsidy for Mobile Internet | 移动互联网补贴
A subsidy on mobile data plans lowers the price consumers pay, boosting the quantity of internet subscriptions. Graphically, the subsidy shifts the supply curve for mobile internet to the right, reducing the market price and increasing consumption. Because smartphones and data plans are complements, this also shifts the demand curve for smartphones to the right. The size of the smartphone demand shift depends on the cross-price elasticity of -0.5: a given percentage fall in data plan prices leads to half that percentage increase in smartphone demand.
对移动数据套餐的补贴降低了消费者支付的价格，增加了互联网订阅量。在图形上，补贴使移动互联网的供给曲线右移，降低市场价格并增加消费量。由于智能手机和数据套餐是互补品，这也会使智能手机的需求曲线右移。智能手机需求移动的幅度取决于交叉弹性-0.5：数据套餐价格每下降一定百分比，智能手机需求就增加该百分比的一半。
This dual policy mix creates a tension: the tariff pushes smartphone prices up and risks reducing digital inclusion, while the internet subsidy makes connectivity cheaper and encourages smartphone ownership. An effective evaluation must weigh which effect dominates, taking note of the different time horizons and the relative sizes of the tariff and subsidy.
这种双重政策组合产生了张力：关税推高智能手机价格，可能削弱数字包容性；而互联网补贴使连接更便宜，鼓励人们拥有智能手机。有效的评估必须衡量哪种效应占主导地位，同时注意不同的时间跨度和关税与补贴的相对规模。
8. Impacts on Key Stakeholders | 对主要利益相关者的影响
Consumers: Face higher smartphone prices, reducing their real income. Low-income groups are disproportionately affected, raising equity concerns.
Domestic workers: The assembly industry's 5,000 employees may see greater job security and perhaps wage rises, although much depends on the industry's ability to scale up.
Government: Collects tariff revenue that could be used to fund the internet subsidy or other public services. It may also gain political support from protecting domestic jobs.
Foreign producers: Experience a fall in export quantity to Country X, though inelastic demand limits the volume drop. Some may absorb part of the tariff to remain competitive.
Society overall: Benefits from lower electronic waste if consumption falls, but also faces potential digital divide issues if smartphones become less accessible.
消费者：面临更高的智能手机价格，实际收入减少。低收入群体受到的不成比例影响引发了公平性担忧。
本国工人：组装业的5000名员工可能获得更大的就业保障甚至是工资上涨，尽管这在很大程度上取决于该行业扩张的能力。
政府：获得关税收入，可用于为互联网补贴或其他公共服务提供资金。还可能因保护国内就业而获得政治支持。
外国生产者：对X国出口量下降，但缺乏弹性的需求限制了降幅。部分生产商可能自行消化部分关税以保持竞争力。
整体社会：如果消费下降，能从电子垃圾减少中受益，但若智能手机变得不易获取，也可能面临数字鸿沟问题。
9. Policy Evaluation and Long-run Consequences | 政策评估与长期后果
In the short run, the tariff is likely to raise government revenue and protect some jobs, but it makes smartphones more expensive and does little to address the trade deficit if imports remain largely unchanged. The internet subsidy partially offsets these costs and generates positive externalities. In the long run, however, protecting an infant industry without competition may breed inefficiency. A better alternative might be a targeted tax on electronic waste combined with direct support for digital training, rather than an across-the-board import tariff.
短期内，关税很可能会增加政府收入并保护一些工作岗位，但会使智能手机变得更贵，而且在进口量基本保持不变的情况下，对解决贸易逆差作用甚微。互联网补贴部分抵消了这些成本，并产生了正外部性。然而，长期来看，在没有竞争的情况下保护幼稚产业可能导致效率低下。一个更好的替代方案或许是针对电子垃圾征税，并结合对数字培训的直接支持，而不是一刀切的进口关税。
You should always consider unintended consequences. For instance, the tariff might encourage smuggling or grey markets, reducing its effectiveness and generating criminality. Additionally, if the local assembly industry fails to become internationally competitive, workers might need retraining once protection is removed.
你始终要考虑意外后果。例如，关税可能会助长走私或灰色市场，削弱其效果并滋生犯罪。此外，如果本地组装业未能具备国际竞争力，一旦保护取消，工人可能需要再培训。
10. Practice Questions and Model Answers | 练习题与示范答案
Question 1: Discuss whether the government of Country X should impose the 10% tariff on smartphones. [6 marks]
Model answer (extract): plier effect in the local economy. However, smartphones are price inelastic (PED = -0.8), so consumers will pay significantly higher prices, worsening inequality for low-income households. The tariff also raises government revenue, which could fund the internet subsidy. But as the import quantity does not fall much, the trade deficit improvement might be minimal. On balance, the tariff hurts consumers disproportionately, and a more targeted policy might be preferable.
问题1：讨论X国政府是否应该对智能手机征收10%的关税。[6分]
示范答案（摘要）：
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