📚 IB Economics: Final Revision Guide | IB 经济：期末复习提纲
As the end of term approaches, it is vital to consolidate the core concepts of the IB Economics syllabus. This revision guide breaks down the essential topics across microeconomics, macroeconomics, international economics, and development, providing you with clear explanations, key formulas, and common exam pitfalls. Use it to structure your revision and test your understanding before the final assessment.
随着学期结束的临近，巩固IB经济学大纲中的核心概念至关重要。这份复习提纲分解了微观经济学、宏观经济学、国际经济学和发展经济学中的基本主题，为你提供清晰的解释、关键公式和常见考试误区。用它来规划你的复习，并在最终评估前检验你的理解。
1. Scarcity and Choice | 稀缺性与选择
Scarcity is the fundamental economic problem: unlimited human wants confront limited resources. This condition forces all economic agents—individuals, firms, and governments—to make choices, which inevitably involve opportunity cost, defined as the value of the next best alternative forgone.
稀缺性是根本的经济问题：无限的欲望与有限的资源相遇。这种状况迫使所有经济主体——个人、企业和政府——做出选择，这些选择必然涉及机会成本，即所放弃的次优选择的价值。
The three basic economic questions that every society must answer are: What to produce? How to produce? For whom to produce?
每个社会必须回答的三个基本经济问题是：生产什么？如何生产？为谁生产？
A production possibilities curve (PPC) illustrates these concepts. Points on the curve show maximum possible output combinations of two goods given existing resources and technology, while points inside indicate inefficiency or unemployment. An outward shift of the PPC represents economic growth, caused by increases in the quantity or quality of resources or technological progress.
生产可能性曲线（PPC）展示了这些概念。曲线上的点表示在现有资源和技术下两种商品的最大可能产出组合，而曲线内的点则代表低效率或失业。PPC向外移动代表经济增长，这源于资源数量或质量的提升或技术进步。
Remember: opportunity cost increases as you move along a concave PPC, due to the law of increasing opportunity cost—resources are not equally suited to producing all goods.
记住：沿凹向原点的PPC移动时机会成本递增，这源于机会成本递增定律——资源并非同等适合生产所有商品。
2. Demand and Supply | 需求与供给
The law of demand states that, ceteris paribus, as the price of a good rises, the quantity demanded falls, resulting in a downward‑sloping demand curve. The law of supply states that as price rises, quantity supplied increases, leading to an upward‑sloping supply curve.
需求定律指出，在其他条件不变的情况下，商品价格上升，需求量下降，形成向下倾斜的需求曲线。供给定律指出，价格上升，供给量增加，形成向上倾斜的供给曲线。
Market equilibrium occurs where quantity demanded equals quantity supplied. At prices above equilibrium, a surplus exists, putting downward pressure on price; below equilibrium, a shortage drives price up.
市场均衡发生在需求量等于供给量之处。价格高于均衡时出现过剩，对价格施加下行压力；低于均衡时出现短缺，推动价格上升。
Shifts in the demand curve are caused by changes in non‑price determinants: income (normal vs. inferior goods), preferences, prices of related goods (substitutes and complements), and expectations. Supply shifts result from changes in input costs, technology, taxes/subsidies, and the number of sellers.
需求曲线的移动由非价格决定因素引起：收入（正常品与劣等品）、偏好、相关商品价格（替代品和互补品）以及预期。供给移动源于投入成本、技术、税收/补贴以及卖方数量的变化。
Qd = a − bP Qs = c + dP
Be able to distinguish between a movement along the curve (change in price) and a shift of the curve. Diagrams are essential—always label axes, curves, and equilibrium points clearly.
要能区分沿着曲线的移动（价格变动）和曲线的平移。图表至关重要——务必清晰标注轴、曲线和均衡点。
3. Elasticity | 弹性
Price elasticity of demand (PED) measures the responsiveness of quantity demanded to a change in price. It is calculated as:
需求价格弹性（PED）衡量需求量对价格变化的反应程度。计算公式为：
PED = %ΔQd / %ΔP
| Value | Classification | Revenue relationship |
|---|---|---|
| |PED| > 1 | Price elastic | Price ↑ → TR ↓ |
| |PED| < 1 | Price inelastic | Price ↑ → TR ↑ |
| |PED| = 1 | Unit elastic | TR unchanged |
Determinants of PED include the number and closeness of substitutes, the proportion of income spent on the good, the degree of necessity, and the time period. For exam success, always link elasticity to the firm’s pricing strategy and government tax revenue.
PED的决定因素包括替代品的数量与相近程度、商品支出占收入的比例、必需品程度以及时间周期。为了考试成功，务必把弹性与企业的定价策略和政府税收收入联系起来。
Income elasticity (YED) indicates how demand changes as income changes; a positive YED signals a normal good, while a negative YED indicates an inferior good. Cross‑price elasticity (XED) reveals relationships between goods: positive for substitutes, negative for complements.
收入弹性（YED）表明需求如何随收入变化而变化；正YED表示正常品，负YED表示劣等品。交叉弹性（XED）揭示商品间的关系：正值为替代品，负值为互补品。
Price elasticity of supply (PES) measures the responsiveness of quantity supplied to a price change. Key determinants are the mobility of factors of production, the ability to store stocks, spare capacity, and time period. Draw and analyse the five PED/PES cases using diagrams.
供给价格弹性（PES）衡量供给量对价格变化的反应程度。关键决定因素有生产要素的流动性、存储能力、闲置产能和时间周期。请用示意图画出并分析PED/PES的五种情况。
4. Government Intervention | 政府干预
Governments often intervene in markets to correct perceived market failures or to achieve equity goals. Common forms include price controls (ceilings and floors), indirect taxes (specific and ad valorem), and subsidies.
政府经常干预市场以纠正感知的市场失灵或实现公平目标。常见形式包括价格管制（上限和下限）、间接税（从量税和从价税）以及补贴。
A price ceiling set below equilibrium creates a persistent shortage, often leading to black markets and reduced quality. A price floor (e.g., minimum wage or agricultural support) above equilibrium generates a surplus that the government may need to purchase.
设定在均衡价格以下的价格上限会造成持续短缺，往往导致黑市和质量下降。设定在均衡价格以上的价格下限（如最低工资或农业支持）会产生过剩，政府可能需要收购。
An indirect tax shifts the supply curve vertically upward by the amount of the tax. The burden is shared between consumers and producers depending on relative elasticities: the more inelastic side bears a greater proportion. Subsidies shift the supply curve downward, increasing quantity and lowering consumer price.
间接税使供给曲线向上垂直移动税额的幅度。负担在消费者和生产者之间分担，取决于相对弹性：更缺乏弹性的一方承担更大比例。补贴使供给曲线向下移动，增加数量并降低消费者支付的价格。
Always illustrate welfare effects: identify consumer surplus, producer surplus, government revenue/expenditure, and deadweight loss on your diagram. Be ready to evaluate the effectiveness and consequences of these interventions.
始终要说明福利效应：在图中标出消费者剩余、生产者剩余、政府收入/支出和无谓损失。准备好评价这些干预措施的有效性和后果。
5. Market Failure | 市场失灵
Market failure occurs when the free market, left to itself, fails to allocate resources efficiently, leading to a net social loss. The main causes are externalities, public goods, common access resources, and information asymmetry.
当自由市场听之任之时无法有效配置资源导致社会净损失，市场失灵就发生了。主要成因包括外部性、公共品、公共资源以及信息不对称。
Negative production externalities (e.g., pollution) cause over‑production and a welfare loss because producers ignore external costs. Positive consumption externalities (e.g., education) cause under‑consumption. Draw the MSC/MSB curves to show socially optimal output versus market output.
负生产外部性（如污染）导致过度生产和福利损失，因为生产者忽视了外部成本。正消费外部性（如教育）导致消费不足。画出边际社会成本/边际社会收益曲线，显示社会最优产量与市场产量的对比。
Public goods are non‑rivalrous and non‑excludable, leading to the free‑rider problem. Common access resources (e.g., fisheries) are rivalrous but non‑excludable, creating the tragedy of the commons. Policy responses include Pigouvian taxes, cap‑and‑trade, legislation, and awareness campaigns.
公共品具有非竞争性和非排他性，导致搭便车问题。公共资源（如渔业）具有竞争性但非排他性，造成公地悲剧。政策应对措施包括庇古税、排污权交易、立法和宣传运动。
When evaluating policies, discuss market‑based vs. command‑and‑control approaches, considering efficiency, equity, and practical limitations.
评价政策时，要讨论市场化方法与命令控制型方法的优劣，考虑效率、公平和实际局限性。
6. Macroeconomic Objectives and Measurement | 宏观经济目标与测量
Governments generally pursue four main macroeconomic objectives: sustainable economic growth, low and stable inflation, low unemployment, and a sustainable balance of payments. A fifth objective, greater income equality, may also be considered.
政府通常追求四大宏观经济目标：可持续经济增长、低且稳定的通货膨胀、低失业率以及可持续的国际收支。第五个目标——更平等的收入分配——也常被考虑在内。
Gross Domestic Product (GDP) measures the total value of all final goods and services produced within a country in a given period. It can be calculated via the expenditure approach: GDP = C + I + G + (X − M). Real GDP strips out price changes to measure actual output.
国内生产总值（GDP）衡量一国在特定时期内生产的全部最终商品与服务的总价值。可通过支出法计算：GDP = C + I + G + (X − M)。实际GDP剔除了价格变动以衡量实际产出。
Inflation is commonly measured by the Consumer Price Index (CPI). A rise in the CPI indicates a fall in the purchasing power of money. Deflation and disinflation are distinct concepts: deflation is a general drop in prices, while disinflation is a slowdown in the inflation rate.
通货膨胀通常用消费者价格指数（CPI）衡量。CPI上升表明货币购买力下降。通货紧缩与反通货膨胀是不同的概念：通货紧缩指价格普遍下降，反通货膨胀则是通胀率的放缓。
Unemployment is measured by the labour force survey and can be categorised as cyclical, structural, frictional, and seasonal. The balance of payments consists of the current account, capital account, and financial account. A current account deficit must be matched by a surplus on the capital/financial account.
失业通过劳动力调查衡量，可分为周期性、结构性、摩擦性和季节性失业。国际收支由经常账户、资本账户和金融账户组成。经常账户赤字必须由资本/金融账户的盈余来匹配。
7. Aggregate Demand and Aggregate Supply | 总需求与总供给
Aggregate demand (AD) represents the total spending on domestic goods and services at a given price level. Its components are consumption (C), investment (I), government spending (G), and net exports (X − M). The AD curve is downward‑sloping due to the wealth effect, interest‑rate effect, and net export effect.
总需求（AD）代表在给定价格水平下对国内商品与服务的总支出。其组成部分为消费（C）、投资（I）、政府支出（G）和净出口（X − M）。由于财富效应、利率效应和净出口效应，AD曲线向下倾斜。
Short‑run aggregate supply (SRAS) is upward‑sloping because, in the short run, costs such as wages are sticky. The long‑run aggregate supply (LRAS) is vertical at the full‑employment level of output (potential GDP), assuming classical neutrality of money. Shifts in LRAS reflect changes in the quantity and quality of factors of production.
短期总供给（SRAS）向上倾斜，因为短期内工资等成本具有粘性。长期总供给（LRAS）在充分就业产出水平（潜在GDP）处为垂直线，这基于古典货币中性假设。LRAS的移动反映生产要素数量与质量的变化。
An increase in AD in the short run raises both output and the price level; in the long run, if the economy is at full employment, further AD increases only cause inflation. Supply‑side shocks (e.g., higher oil prices) shift SRAS left, causing stagflation.
短期中AD增加既提高产出又提高价格水平；长期中，如果经济处于充分就业，AD进一步增加只会导致通胀。供给侧冲击（如油价上涨）使SRAS左移，引发滞胀。
8. Macroeconomic Policies | 宏观经济政策
Fiscal policy involves changes in government spending and taxation. Expansionary fiscal policy (higher G, lower T) aims to boost AD during a recession; contractionary policy cools an overheating economy. Automatic stabilisers, such as progressive taxation and unemployment benefits, operate without discretionary action.
财政政策涉及政府支出和税收的变化。扩张性财政政策（增加G，降低T）旨在衰退期间刺激AD；紧缩性政策则为过热经济降温。自动稳定器，如累进税制和失业救济，无需斟酌行动即可发挥作用。
Monetary policy, managed by the central bank, uses interest rates and the money supply to influence AD. Lower interest rates encourage borrowing and investment, while higher rates curb inflation. Quantitative easing is an unconventional tool used when policy rates approach zero.
由中央银行管理的货币政策运用利率和货币供给影响AD。降低利率鼓励借贷和投资，而提高利率抑制通胀。量化宽松是政策利率接近零时使用的非常规工具。
Supply‑side policies aim to increase the economy’s productive capacity by improving the efficiency and flexibility of markets. Examples include education and training, tax reforms, deregulation, labour market reforms, and infrastructure investment. Evaluate their time lags and effectiveness in achieving long‑term growth versus demand‑side policies.
供给侧政策旨在通过提高市场效率和灵活性来增加经济的生产能力。例子包括教育和培训、税制改革、放松监管、劳动力市场改革以及基础设施投资。要评估这些政策相对于需求管理政策在实现长期增长方面的时滞和有效性。
9. International Trade and Protectionism | 国际贸易与保护主义
The theory of comparative advantage, developed by David Ricardo, demonstrates that countries can benefit from specialisation and trade even if one country holds an absolute advantage in all goods. The gains arise from differences in opportunity costs.
大卫·李嘉图提出的比较优势理论表明，即使一国在所有商品上均具有绝对优势，各国仍可通过专业化和贸易获益。收益源于机会成本的差异。
Protectionism refers to policies that shield domestic industries from foreign competition. Common tools include tariffs (taxes on imports), quotas (quantitative limits), subsidies to domestic producers, and administrative barriers. A tariff raises the domestic price, reduces imports, and creates a deadweight loss, but may protect infant industries or jobs.
保护主义指保护国内产业免受外国竞争的政策。常见工具包括关税（进口税）、配额（数量限制）、对国内生产者的补贴以及行政壁垒。关税提高了国内价格，减少了进口，并造成无谓损失，但可能保护幼稚产业或就业。
When evaluating protectionism, consider arguments for (protecting infant industries, anti‑dumping, strategic trade) and against (higher costs for consumers, inefficiency, retaliation). Draw the tariff diagram showing consumer surplus loss, producer surplus gain, government revenue, and deadweight loss.
评价保护主义时，考虑支持观点（保护幼稚产业、反倾销、战略性贸易）和反对观点（消费者成本上升、低效率、报复）。画出关税示意图，标明消费者剩余损失、生产者剩余收益、政府收入和无谓损失。
10. Exchange Rates and Balance of Payments | 汇率与国际收支
An exchange rate is the price of one currency in terms of another. It can be determined in a floating system by supply and demand, fixed by the central bank, or managed in a managed float. Appreciation makes exports more expensive and imports cheaper; depreciation has the opposite effect.
汇率是一种货币以另一种货币表示的价格。它可以在浮动汇率制下由供求决定，也可以由中央银行固定，或在管理浮动制下管理。升值使出口更贵、进口更便宜；贬值则产生相反效应。
The current account of the balance of payments records trade in goods, services, primary income, and secondary income. A current account deficit must be financed by a surplus on the financial/capital account, implying net borrowing from abroad. Persistent deficits may raise concerns about external debt sustainability.
国际收支中的经常账户记录货物、服务、初次收入和二次收入。经常账户赤字必须由金融/资本账户的盈余来融资，这意味着从国外净借款。持续的赤字可能引发对外部债务可持续性的担忧。
The Marshall‑Lerner condition states that a currency depreciation improves the trade balance only if the sum of price elasticities of demand for exports and imports is greater than one (in absolute value). Illustrate using the J‑curve effect, which shows an initial worsening before the trade balance improves.
马歇尔‑勒纳条件指出，只有当出口和进口的需求价格弹性绝对值之和大于1时，货币贬值才会改善贸易差额。用J曲线效应加以说明，该效应表明贸易差额在改善前先出现恶化。
11. Economic Development and Growth | 经济发展与增长
Economic growth refers to an increase in a country’s real GDP over time, while economic development is a broader concept encompassing improvements in living standards, health, education, and human freedoms. Common indicators include GDP per capita, the Human Development Index (HDI), and the Multidimensional Poverty Index.
经济增长指的是一国实际GDP随时间增长，而经济发展是一个更宽泛的概念，包括生活水平、健康、教育和人的自由等方面的改善。常用指标有人均GDP、人类发展指数（HDI）和多维贫困指数。
Barriers to development include inadequate infrastructure, low human capital, political instability, corruption, and the poverty trap. International trade strategies such as import substitution and export promotion have been used with varying success. Foreign aid, microfinance, and debt relief are also key instruments.
发展的障碍包括基础设施不足、人力资本低下、政局不稳定、腐败以及贫困陷阱。进口替代和出口促进等国际贸易战略取得了不同程度的成功。外国援助、小额信贷和债务减免也是关键工具。
In your essays, distinguish between growth and development, and evaluate policies like foreign direct investment (FDI) or trade liberalisation in terms of their ability to foster both higher GDP and improved well‑being.
在论文中，区分增长与发展，并从促进更高GDP和改善福祉两方面来评价外国直接投资（FDI）或贸易自由化等政策。
12. Exam Tips and Common Mistakes | 考试技巧与常见误区
Always define key terms in your own words before applying them; this demonstrates understanding and secures marks. Use precise economic terminology—e.g., ‘extension of demand’ for a movement down a demand curve, not ‘increase in demand’ which implies a shift.
总是先用自己的话给关键术语下定义，然后再应用它们；这能展示理解并确保得分。使用精确的经济学术语——例如，沿需求曲线向下移动用“需求量扩大”，而不是“需求增加”，后者意味着平移。
In data‑response questions, explicitly quote figures from the text, calculate ratios or percentage changes, and relate them to the economic theory. For essays, structure your answer with introduction, analysis, evaluation, and a reasoned conclusion. Always include well‑labelled diagrams, even when not explicitly asked; they often earn credit.
在数据分析题中，明确引用文中的数字，计算比率或百分比变化，并将其与经济学理论联系起来。对于论文，按照引言、分析、评估和有理有据的结论来组织答案。务必附上标注清晰的示意图，即使没有明确要求也应当如此；它们通常能得分。
Common mistakes include: confusing a shift of the curve with a movement along it; mixing up real and nominal variables; stating ‘the government increases spending’ without specifying how it is financed; and providing one‑sided evaluation. Practice drawing and explaining at least ten core diagrams until they are second nature.
常见错误包括：混淆曲线平移与沿线移动；混淆实际变量与名义变量；仅说“政府增加支出”而未说明融资方式；以及给予片面评价。练习绘制并解释至少十个核心示意图，直到它们成为你的本能反应。
Finally, manage your time wisely: in Paper 1 allocate about 30 minutes per essay, and in Paper 2 and 3, answer the required number of questions without over‑elaborating on a single part.
最后，明智地管理时间：试卷1中每道论文题分配约30分钟，试卷2和3中回答要求数量的题，不要在单一小题上过度发挥。
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