📚 IB Edexcel Economics: Last-Minute Revision Notes | IB 爱德思经济：考前冲刺笔记
As exam day approaches, a sharp, bilingual recap of the most essential economic concepts can make all the difference. This condensed study guide blends core IB and Edexcel Economics topics into a single, clear pathway, giving you the confidence to tackle multiple-choice, data-response and essay questions.
考试临近，一份凝练的双语核心考点回顾往往能让你事半功倍。这份冲刺笔记将 IB 与爱德思经济学的必考主题融为一体，用清晰的逻辑帮你从容应对选择题、材料分析题和论述题。
1. Demand and Supply | 需求与供给
The law of demand states that as price falls, quantity demanded rises, ceteris paribus. The demand curve shifts when non-price determinants such as income, tastes, prices of related goods, expectations and number of consumers change.
需求定律指出，在其他条件不变的情况下，价格下跌则需求量上升。当收入、偏好、相关商品价格、预期和消费者数量等非价格因素变动时，需求曲线会发生平移。
The law of supply holds that higher prices encourage greater quantity supplied because they raise the profitability of production. Supply shifts stem from changes in input costs, technology, indirect taxes, subsidies, number of sellers and weather.
供给定律认为，价格越高，供给量越大，因为生产利润增加。投入成本、技术、间接税、补贴、供应商数量和天气等变化都会导致供给曲线平移。
Market equilibrium occurs where quantity demanded equals quantity supplied. Any shift in either curve results in a new equilibrium price and quantity, and the price mechanism allocates scarce resources efficiently in free markets.
市场均衡出现在需求量等于供给量之处。任一曲线移动都会形成新的均衡价格与均衡数量，在自由市场中价格机制能有效配置稀缺资源。
2. Elasticity | 弹性
Price elasticity of demand (PED) measures the responsiveness of quantity demanded to a price change. Its formula is:
需求价格弹性(PED)衡量需求量对价格变动的反应程度，计算公式如下：
PED = %ΔQd / %ΔP
The table below classifies PED values and their impact on total revenue (TR).
下表对 PED 取值进行了分类，并说明了价格上升时对总收入(TR)的影响。
| |PED| | Classification | TR when P ↑ |
|---|---|---|
| > 1 | Elastic | Falls |
| = 1 | Unit elastic | Unchanged |
| < 1 | Inelastic | Rises |
Income elasticity of demand (YED) links quantity demanded to consumer income; normal goods have YED > 0, while inferior goods have YED < 0. Cross-price elasticity (XED) is positive for substitutes and negative for complements.
收入弹性(YED)反映需求量与收入的关系，正常品的 YED > 0，低档品的 YED < 0。交叉价格弹性(XED)在替代品间为正，互补品间为负。
Price elasticity of supply (PES) measures how easily producers can adjust output. It depends on the time period, spare capacity, stock levels and the complexity of production.
供给价格弹性(PES)衡量生产者调整产量的难易程度，取决于时间长短、闲置产能、库存水平和生产复杂度。
3. Government Intervention | 政府干预
Maximum prices (ceilings) are set below equilibrium to protect consumers but often create shortages. Minimum prices (floors) are set above equilibrium to support producers and may lead to excess supply.
最高限价设置于均衡价格之下以保护消费者，但常引发短缺；最低限价设置于均衡价格之上以支持生产者，却可能导致过剩。
Indirect taxes shift the supply curve leftwards, raising price and reducing quantity. The burden of tax falls more heavily on the side of the market that is less elastic – a concept shown by the tax incidence diagram.
间接税使供给曲线左移，推高价格、降低交易量。税收负担更多地落在弹性较小的一方——这通常用税收归宿图来展示。
Subsidies shift supply rightwards, lowering price and increasing output. Governments also intervene through regulation, direct provision of public goods and information campaigns to correct market failures.
补贴使供给曲线右移，降低价格、扩大产量。政府还通过法规、直接提供公共品和信息宣传等手段纠正市场失灵。
4. Market Failure | 市场失灵
Negative production externalities occur when marginal social cost (MSC) exceeds marginal private cost (MPC). The welfare loss triangle appears because the market overproduces from society’s viewpoint.
负生产外部性发生在边际社会成本(MSC)大于边际私人成本(MPC)时。从社会角度看市场生产过度，产生福利损失三角。
Positive consumption externalities arise when marginal social benefit (MSB) outweighs marginal private benefit (MPB). The free market will under‑consume such merit goods, justifying government subsidies.
正消费外部性出现在边际社会收益(MSB)大于边际私人收益(MPB)时。自由市场对这类优值品消费不足，为补贴提供了理由。
MSC = MPC + MEC
MSB = MPB + MEB
Public goods are non‑excludable and non‑rivalrous, leading to the free‑rider problem. Common pool resources suffer from over‑exploitation unless sustainable management is imposed.
公共品具有非排他性和非竞争性，导致搭便车问题。公共池塘资源若无可持续管理，便会遭到过度开发。
5. Market Structures | 市场结构
Perfect competition features many firms, homogeneous products and no barriers to entry. In the short run, firms can earn supernormal profit, but in the long run they only make normal profit as new entrants shift supply rightwards.
完全竞争市场中企业众多、产品同质、无进入壁垒。短期内企业可获超额利润，但长期中因新企业进入、供给右移，只能获得正常利润。
ges a price above marginal cost, leading to allocative inefficiency and a deadweight loss.
垄断指单一卖方且进入壁垒高。垄断者按 MR = MC 确定产量，但定价高于边际成本，造成配置无效和净损失。
Monopolistic competition combines many firms with differentiated products. Oligopoly is characterised by a few interdependent firms, often modelled by the kinked demand curve and game theory.
垄断竞争拥有众多企业及差异化产品。寡头垄断由少数相互依存的企业组成，常用弯折的需求曲线和博弈论来解释。
6. Macroeconomic Objectives | 宏观经济目标
Governments aim for sustained economic growth (rising real GDP), low unemployment, stable prices (low inflation), a balanced current account and a more equal distribution of income. These goals can conflict, e.g. rapid growth may worsen inflation and the trade balance.
政府的政策目标通常包括持续的经济增长、低失业、物价稳定、国际收支平衡以及更公平的收入分配。这些目标之间可能存在冲突，例如高速增长可能加剧通胀并恶化贸易收支。
Unemployment is measured by the claimant count or the ILO labour force survey. Types include cyclical (demand‑deficient), structural, frictional and seasonal.
失业通过申请失业金人数或国际劳工组织劳动力调查来衡量，类型包括周期性、结构性、摩擦性和季节性失业。
Inflation is commonly measured by the Consumer Price Index (CPI). Demand‑pull inflation arises from too much aggregate demand, while cost‑push inflation stems from rising production costs.
通货膨胀通常用消费者价格指数(CPI)测量。需求拉动型通胀源于总需求过旺，成本推动型通胀则来自生产成本上升。
7. Aggregate Demand and Supply | 总需求与总供给
Aggregate demand (AD) is the total spending on goods and services in an economy. The AD equation is:
总需求(AD)是经济中商品和服务的总支出，公式为：
AD = C + I + G + (X − M)
Shifts in AD can be caused by changes in consumer confidence, wealth, interest rates, business expectations, government spending and net exports.
消费者信心、财富、利率、商业预期、政府支出和净出口等因素的变化会引起总需求曲线的移动。
Short‑run aggregate supply (SRAS) is upward‑sloping because of sticky wages and input prices. Long‑run aggregate supply (LRAS) is vertical at full‑employment output in the classical model, while Keynesians argue that LRAS can be horizontal below full employment.
由于工资和投入价格具有粘性，短期总供给曲线(SRAS)向右上方倾斜。古典模型中长期总供给(LRAS)在充分就业产出水平处垂直，而凯恩斯学派认为在未达充分就业时 LRAS 可以是水平的。
8. Fiscal and Monetary Policy | 财政与货币政策
Expansionary fiscal policy involves increasing government spending or cutting taxes to boost AD. Contractionary fiscal policy does the opposite to cool an overheating economy. Automatic stabilisers, such as progressive taxes and welfare benefits, work without new legislation.
扩张性财政政策通过增加政府支出或减税来刺激总需求；紧缩性财政政策则相反，用于给过热的经济降温。累进税和福利支出等自动稳定器无需新的立法便可发挥调节作用。
Monetary policy is conducted by central banks, mainly through setting benchmark interest rates. Lower rates encourage borrowing and investment, while higher rates dampen demand. Quantitative easing (QE) injects liquidity by purchasing government bonds.
货币政策由央行执行，主要通过设定基准利率来调节。降息鼓励借贷和投资，加息抑制需求。量化宽松(QE)则是通过购买政府债券向市场注入流动性。
Supply‑side policies aim to increase the productive capacity of the economy. Examples include education and training, lower income taxes to incentivise work, deregulation and privatisation.
供给侧政策旨在提高经济的生产能力，例如加强教育培训、降低所得税以激励工作、放松管制和私有化。
9. International Trade | 国际贸易
Comparative advantage explains why countries gain from trade even if one country is absolutely more efficient in all goods. The theory is based on differing opportunity costs.
比较优势理论说明，即使一国在所有商品上都具有绝对优势，通过贸易仍可获益，其基础是机会成本的差异。
Protectionist measures include tariffs (taxes on imports), quotas (quantitative limits), subsidies to domestic producers and non‑tariff barriers. They can protect infant industries and jobs but raise prices and reduce choice for consumers.
贸易保护措施包括关税（对进口商品征税）、配额（数量限制）、对国内生产者的补贴以及非关税壁垒。保护可帮助幼稚产业和就业，但会抬高价格并减少消费者选择。
Trading blocs and the World Trade Organization (WTO) promote trade liberalisation. Free trade agreements eliminate barriers among members, while customs unions also adopt a common external tariff.
贸易集团和世界贸易组织(WTO)推动贸易自由化。自由贸易协定取消成员间壁垒，关税同盟则进一步采用共同的对外关税。
10. Exchange Rates and Balance of Payments | 汇率与国际收支
A floating exchange rate is determined by market forces of supply and demand for a currency. Depreciation makes exports cheaper and imports dearer, while appreciation has the opposite effect.
浮动汇率由外汇市场的供求决定。货币贬值使出口更便宜、进口更贵，升值则产生相反效果。
The Marshall‑Lerner condition states that a depreciation will improve the current account if the sum of price elasticities of demand for exports and imports is greater than 1. The J‑curve shows a short‑term worsening before an improvement.
马歇尔‑勒纳条件指出，当出口与进口需求价格弹性之和大于 1 时，贬值才能改善经常账户。J 曲线效应则显示短期内经常账户先恶化后改善。
The balance of payments consists of the current account (trade in goods, services, income and transfers), the capital account and the financial account, which must balance overall.
国际收支平衡表由经常账户（商品、服务、收入和转移）、资本账户和金融账户构成，整体上必须平衡。
11. Development Economics | 发展经济学
Development goes beyond GDP growth and includes improvements in education, health and living standards, often measured by the Human Development Index (HDI). The poverty cycle highlights how low savings and investment trap countries in poverty.
发展不仅指 GDP 增长，还包括教育、健康和生活水准的提升，常用人类发展指数(HDI)来衡量。贫困恶性循环说明了低储蓄与低投资如何使国家陷于贫困。
Barriers to development include primary product dependency, poor infrastructure, weak governance, high debt burdens and lack of access to capital. Market‑based strategies favour trade liberalisation and FDI, while interventionist approaches stress the role of government planning.
发展障碍包括初级产品依赖、基础设施薄弱、治理不善、沉重的债务负担和资本缺乏。市场化策略主张贸易自由化与外国直接投资，干预主义策略则强调政府规划的作用。
Foreign direct investment (FDI) can bring capital, technology and jobs, but may also lead to profit repatriation and environmental degradation. Aid effectiveness depends on governance, targeting and donor coordination.
外国直接投资(FDI)能带来资本、技术和就业，但也可能导致利润汇回和环境恶化。援助的效果取决于治理水平、精准度和捐助方的协调。
12. Key Diagrams and Formulas | 重要图表与公式
Exam success often rests on accurate diagrams and precise formulations. Practice drawing and labelling these essential models:
考试中能否准确画出并标注关键图表、写出精确公式，往往决定了成绩的高低。请反复练习以下核心模型：
Demand and supply shifts, maximum/minimum price, indirect tax and subsidy diagrams, negative externality with MSC/MPC, positive externality with MSB/MPB, monopoly equilibrium vs. competitive market, AD/AS (both classical and Keynesian), tariff diagram showing deadweight loss, J‑curve and Lorenz curve for income inequality.
需求与供给平移、最高/最低限价、间接税与补贴、负外部性 MSC/MPC、正外部性 MSB/MPB、垄断均衡与竞争市场对比、古典与凯恩斯 AD/AS、关税的无谓损失图、J 曲线以及体现收入不平等的洛伦兹曲线。
Memorise these formulas and use them correctly in calculations:
熟记以下公式，并能在计算中准确运用：
PED = %ΔQd / %ΔP
YED = %ΔQd / %ΔY
XED = %ΔQd of good A / %ΔP of good B
Multiplier = 1 / (1 − MPC) = 1 / (MPS + MPT + MPM)
Terms of trade index = (Export price index / Import price index) × 100
For each diagram, state the initial equilibrium, show the shift, mark the new equilibrium and label the welfare or efficiency implications. Link every curve shift back to a real‑world cause mentioned in the exam stem.
每画一张图，都应标出初始均衡，画出曲线移动，标注新均衡点，并标明福利或效率变化。一定要将每次曲线移动与题目材料中的现实原因联系起来。
Published by TutorHao | Economics Revision Series | aleveler.com
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