📚 Year 13 OCR Economics: Key Terms Quick-Fire Guide | Year 13 OCR 经济：词汇术语速记指南
Mastering the precise language of economics is half the battle in your Year 13 OCR exams. This guide distils essential terms from microeconomics and macroeconomics into bite-sized, bilingual explanations, helping you memorise definitions quickly and use them accurately in essays and data responses.
掌握经济学的精确语言是你 Year 13 OCR 考试成功的一半。这份指南将微观和宏观经济学中的核心术语浓缩为简短的中英双语解释，帮助你快速记忆定义并在论文和数据分析题中准确运用。
1. Marginal Utility and the Law of Diminishing Returns | 边际效用与收益递减规律
Marginal utility is the additional satisfaction a consumer gains from consuming one more unit of a good or service. It underpins the downward-sloping demand curve, as consumers will only buy extra units if the price falls to match the lower marginal benefit.
边际效用是指消费者从多消费一单位商品或服务中获得的额外满足感。它是需求曲线向下倾斜的基础，因为只有当价格下降至与较低的边际收益相匹配时，消费者才会购买额外单位。
The law of diminishing marginal utility states that as consumption increases, the marginal utility derived from each additional unit eventually declines. This explains why demand curves are convex to the origin. In OCR exam analysis, you must link this to the income and substitution effects when explaining why a price change alters quantity demanded.
边际效用递减规律指出，随着消费增加，从每一额外单位中获得的边际效用最终会下降。这解释了为何需求曲线凸向原点。在 OCR 考试分析中，你必须将此与收入效应和替代效应联系起来，解释为什么价格变化会改变需求量。
Total utility is the aggregate satisfaction from all units consumed. It rises at a decreasing rate when marginal utility is positive but diminishing. The point where marginal utility becomes zero marks maximum total utility. Further consumption would generate negative marginal utility, reducing total utility — a frequent multiple-choice trap.
总效用是所有消费单位带来的满足感总和。当边际效用为正但递减时，总效用以递减的速率上升。边际效用为零的点标志着总效用最大化。进一步消费会产生负边际效用，使总效用下降——这是选择题中常见的陷阱。
2. Elasticities: Price, Income and Cross | 弹性：价格弹性、收入弹性和交叉弹性
Price elasticity of demand (PED) measures the responsiveness of quantity demanded to a change in price. Calculated as %ΔQd ÷ %ΔP, a value greater than 1 indicates elastic demand, less than 1 inelastic demand, and exactly 1 unitary elasticity. A perfectly inelastic demand is a vertical line, while perfectly elastic is horizontal.
需求的价格弹性（PED）衡量需求量对价格变化的反应程度。计算公式为 %ΔQd ÷ %ΔP，值大于1表示富有弹性，小于1缺乏弹性，等于1为单位弹性。完全无弹性的需求是一条垂直线，完全弹性则是水平线。
Income elasticity of demand (YED) is %ΔQd ÷ %ΔY. Normal goods have positive YED; luxury goods have YED > 1, while necessities have 0 < YED < 1. Inferior goods have negative YED, meaning demand falls as income rises. Remember that in a recession, inferior goods may see a boost — a real-world application OCR examiners love.
需求的收入弹性（YED）是 %ΔQd ÷ %ΔY。正常商品具有正的 YED；奢侈品的 YED > 1，必需品的 YED 介于 0 和 1 之间。低档商品具有负的 YED，即收入上升时需求下降。请记住，在经济衰退期低档商品可能销量上升——这是 OCR 考官喜欢的现实应用。
Cross-price elasticity of demand (XED) equals %ΔQd of good A ÷ %ΔP of good B. Positive XED indicates substitutes; negative XED indicates complements. The magnitude also signals the strength of the relationship. Firms use XED to anticipate competitor pricing moves and to manage product portfolios.
需求的交叉价格弹性（XED）等于 A 商品需求量变化百分比 ÷ B 商品价格变化百分比。正 XED 表示替代品，负 XED 表示互补品。数值大小也表明了关系的强弱。企业利用 XED 来预测竞争对手的定价动向并管理产品组合。
3. Costs, Revenue and Profit Maximisation | 成本、收益与利润最大化
In the short run, at least one factor of production is fixed, giving rise to the law of diminishing marginal returns. The marginal cost (MC) curve eventually rises because adding variable factors to a fixed one reduces productivity. The average total cost (ATC) curve is U-shaped, intersecting MC at its minimum point.
在短期，至少有一种生产要素是固定的，这就产生了边际报酬递减规律。边际成本（MC）曲线最终上升，因为将可变要素添加到固定要素上会降低生产率。平均总成本（ATC）曲线呈U形，与 MC 相交于其最低点。
Total revenue (TR) = price × quantity. Average revenue (AR) = TR ÷ quantity = price, hence AR is the demand curve. Marginal revenue (MR) is the addition to TR from selling one more unit. For a firm in perfect competition, MR = AR = price. For a monopolist, MR falls faster than AR and can become negative.
总收益（TR）= 价格 × 数量。平均收益（AR）= TR ÷ 数量 = 价格，因此 AR 曲线就是需求曲线。边际收益（MR）是多销售一单位产品带来的总收益增加额。对于完全竞争市场中的企业，MR = AR = 价格。对于垄断企业，MR 下降得比 AR 快，且可能变为负值。
Profit maximisation occurs where MR = MC. In OCR diagrams, always label the profit-maximising output Q1 and show the price on the AR (demand) curve. To illustrate supernormal profit, shade the area between AR and ATC at Q1. In perfect competition, long-run equilibrium yields only normal profit because AR = ATC at the tangency point.
利润最大化出现在 MR = MC 处。在 OCR 的图表中，务必将利润最大化产量标注为 Q1，并在 AR（需求）曲线上标出价格。为表示超额利润，需将 Q1 处 AR 与 ATC 之间的区域涂上阴影。在完全竞争中，长期均衡只产生正常利润，因为在切点处 AR = ATC。
4. Market Structures: From Perfect Competition to Monopoly | 市场结构：从完全竞争到垄断
Perfect competition is characterised by many buyers and sellers, homogeneous products, perfect information, and freedom of entry and exit. Firms are price-takers, and the long-run equilibrium price equals minimum ATC — both allocatively efficient (P = MC) and productively efficient. Use this as a benchmark for comparison.
完全竞争的特征是：大量买卖双方、同质产品、完全信息以及自由进入和退出。企业是价格接受者，长期均衡价格等于最低 ATC——同时实现了配置效率（P = MC）和生产效率。将此作为比较的基准。
Monopolistic competition blends a large number of firms with product differentiation. In the long run, new entrants shift the firm’s demand curve leftwards until it is tangential to ATC — earning normal profit only. The firm remains allocatively inefficient (P > MC) and has excess capacity, a point worth emphasising in evaluation.
垄断竞争结合了众多企业和产品差异化。在长期，新进入者使企业的需求曲线向左移动，直到与 ATC 相切——仅获得正常利润。企业仍然配置无效率（P > MC）且存在产能过剩，这一点在评估中值得强调。
Oligopoly is defined by a few dominant firms, high concentration ratios, interdependence, and barriers to entry. The kinked demand curve model explains price rigidity: if a firm raises price, rivals do not follow, making demand elastic above the kink; if it cuts price, rivals match, making demand inelastic below. This creates a discontinuity in the MR curve, allowing costs to change within a range without affecting price or output.
寡头垄断的定义是少数主导企业、高集中度、相互依赖以及进入壁垒。弯折的需求曲线模型解释了价格刚性：如果一家企业涨价，竞争对手不会跟随，使得弯折点上方的需求富有弹性；如果降价，对手也会跟进，使得弯折点下方的需求缺乏弹性。这导致 MR 曲线出现间断，成本在一定范围内变化时不会影响价格或产量。
Monopoly is a single seller with high barriers to entry. A pure monopolist can earn supernormal profits even in the long run. Third-degree price discrimination is a key term: charging different prices to different consumer groups based on their PED, with no resale. Peak/off-peak rail fares and student discounts are real-world examples. Consumer surplus is extracted and converted into producer surplus.
垄断是指存在单一卖方且进入壁垒很高。纯垄断者即使在长期也能获得超额利润。三级价格歧视是一个关键术语：根据消费者群体的 PED 收取不同价格，且不存在转卖。铁路高峰期/非高峰期票价和学生折扣是现实世界的例子。消费者剩余被榨取并转化为生产者剩余。
5. Labour Market and Wage Determination | 劳动力市场与工资决定
The demand for labour is derived from the demand for the goods and services labour produces. The marginal revenue product of labour (MRPL) = marginal product of labour × marginal revenue. Firms hire where MRPL = wage rate (marginal cost of labour) to maximise profits. The MRPL curve therefore is the labour demand curve.
劳动力需求是对劳动力所生产的商品和服务的派生需求。劳动的边际收益产品（MRPL）= 劳动的边际产量 × 边际收益。企业在 MRPL = 工资率（劳动的边际成本）处雇佣劳动力以实现利润最大化。因此 MRPL 曲线就是劳动力需求曲线。
Elasticity of labour demand depends on the price elasticity of demand for the final product, the ease of substituting capital for labour, the proportion of labour costs in total costs, and time period. Supply of labour is influenced by the wage rate, the reservation wage, barriers to entry (qualifications), and non-monetary factors such as job satisfaction.
劳动力需求弹性取决于最终产品的需求价格弹性、资本替代劳动的难易程度、劳动力成本在总成本中的占比，以及时间长短。劳动力供给受到工资率、保留工资、准入壁垒（资质要求）以及工作满意度等非金钱因素的影响。
Wage differentials arise from differences in MRP, human capital, trade union power, discrimination, and compensating differentials (e.g., risky jobs pay more). Monopsony power in the labour market means a single buyer (e.g., NHS for nurses) can drive wages below competitive levels and reduce employment — a key diagram with an upward-sloping labour supply curve faced by the firm.
工资差异源于 MRP、人力资本、工会力量、歧视以及补偿性差异（例如高风险工作薪酬更高）等方面的不同。劳动力市场中的买方垄断意味着单一买家（如 NHS 雇佣护士）可以将工资压低到竞争性水平以下并减少就业——其关键图示是企业面对的向上倾斜的劳动力供给曲线。
6. Macroeconomic Objectives and Indicators | 宏观经济目标与指标
The key macroeconomic objectives are sustainable economic growth, low and stable inflation (2% in the UK), low unemployment, and a satisfactory balance of payments. Economic growth is measured by the percentage change in real GDP, stripping out inflation to reflect the true increase in the volume of output.
关键的宏观经济目标是可持续的经济增长、低且稳定的通货膨胀（英国目标为 2%）、低失业率以及令人满意的国际收支状况。经济增长通过实际 GDP 的百分比变化衡量，剔除通货膨胀以反映产出量的真实增加。
Inflation is a sustained rise in the general price level. The Consumer Price Index (CPI) is the main measure, but the Retail Price Index (RPI) includes housing costs. Deflation is a persistent fall in the price level, often more damaging than moderate inflation because it encourages consumers to delay spending and increases the real burden of debt.
通货膨胀是一般价格水平的持续上涨。消费者价格指数（CPI）是主要衡量指标，但零售价格指数（RPI）包括了住房成本。通货紧缩是价格水平的持续下跌，通常比温和通胀更具破坏性，因为它鼓励消费者推迟开支并加重债务的实际负担。
Unemployment is measured by the claimant count and the Labour Force Survey (LFS). Types include cyclical (demand-deficient), structural (mismatch of skills), frictional (between jobs), and seasonal. The natural rate of unemployment includes structural and frictional; reducing it requires supply-side policies like training and education.
失业率通过申领人数和劳动力调查（LFS）来衡量。类型包括周期性（需求不足）、结构性（技能错配）、摩擦性（求职间隙）和季节性失业。自然失业率包含结构性和摩擦性失业；降低它需要培训和教育等供给侧政策。
7. Aggregate Demand and Aggregate Supply | 总需求与总供给
Aggregate demand (AD) = C + I + G + (X − M). Consumption is the largest component, driven by disposable income, wealth, interest rates, and consumer confidence. Investment is the most volatile because it depends on business optimism, interest rates, and the accelerator effect — where investment responds to changes in the growth rate of demand, not its level.
总需求（AD）= 消费 C + 投资 I + 政府支出 G + （出口 X − 进口 M）。消费是最大的组成部分，受可支配收入、财富、利率和消费者信心的驱动。投资最为波动，因为它取决于企业乐观情绪、利率以及加速效应——投资是对需求增长率而非其水平的变化作出反应。
Short-run aggregate supply (SRAS) is upward-sloping because wages and some input prices are sticky. Long-run aggregate supply (LRAS) is vertical at the full employment level of output (classical view) or can be upward-sloping if the economy is not at full capacity (Keynesian view). A shift in LRAS represents economic growth, caused by increases in the quantity or quality of factors of production.
短期总供给（SRAS）是向上倾斜的，因为工资和部分投入品价格具有粘性。长期总供给（LRAS）在充分就业产出水平处是垂直的（古典观点），如果经济未达满负荷运转则可能向上倾斜（凯恩斯观点）。LRAS 的移动代表经济增长，由生产要素数量或质量的提高引起。
The multiplier effect occurs when an initial injection into the circular flow leads to a larger final increase in GDP. The formula is 1 ÷ (1 − MPC) or 1 ÷ MPW, where MPC is the marginal propensity to consume and MPW is the marginal propensity to withdraw. The multiplier size is reduced by high leakages (savings, taxes, imports). OCR frequently asks you to evaluate the multiplier’s effectiveness in a recession, considering spare capacity and the state of confidence.
乘数效应发生在对循环流动的初始注入导致最终 GDP 出现更大增长时。公式为 1 ÷ (1 − MPC) 或 1 ÷ MPW，其中 MPC 是边际消费倾向，MPW 是边际漏出倾向。乘数的大小会因高漏出（储蓄、税收、进口）而减小。OCR 经常要求你评估乘数在经济衰退中的有效性，考虑闲置产能和信心状态。
8. Fiscal and Monetary Policy Tools | 财政政策与货币政策工具
Fiscal policy involves government spending and taxation. Expansionary fiscal policy (higher G or lower taxes) aims to boost AD. Automatic stabilisers, such as progressive taxes and welfare benefits, work counter-cyclically without discretionary government action — a key concept for evaluation questions. The budget balance (deficit or surplus) and national debt are constraints on fiscal activism.
财政政策涉及政府支出和税收。扩张性财政政策（增加政府支出或减税）旨在提振总需求。自动稳定器，如累进税和福利津贴，无需政府相机决策即可发挥逆周期作用——这是评估题中的一个关键概念。预算余额（赤字或盈余）和国家债务是财政激进主义的制约因素。
Monetary policy, conducted by the central bank, manipulates interest rates, the money supply, and the exchange rate. A lower base rate reduces borrowing costs, encourages consumption and investment, and typically depreciates the currency, boosting net exports. Quantitative easing (QE) is an unconventional tool where the central bank buys government bonds, injecting liquidity and lowering long-term yields. The transmission mechanism links policy rate changes to real GDP and inflation.
货币政策由央行实施，调控利率、货币供应和汇率。降低基准利率会减少借贷成本，鼓励消费和投资，通常还会使本币贬值，促进净出口。量化宽松（QE）是一种非常规工具，央行通过购买政府债券注入流动性并压低长期收益率。传导机制将政策利率的变化与实际 GDP 和通货膨胀联系起来。
9. International Trade and the Balance of Payments | 国际贸易与国际收支
The balance of payments is divided into the current account, capital account, and financial account. The current account measures trade in goods and services, primary income (investment income), and secondary income (transfers). A deficit means a country is spending more abroad than it earns; it must be financed by net inflows on the financial account.
国际收支分为经常账户、资本账户和金融账户。经常账户衡量商品和服务贸易、初次收入（投资收入）和二次收入（转移支付）。赤字意味着一国在国外的支出超过其收入，必须由金融账户的净流入来融资。
Comparative advantage (David Ricardo) states that countries should specialise in producing goods where they have the lowest opportunity cost, and trade to mutual benefit even if one country has an absolute advantage in all products. Underpinned by differing factor endowments or productivity. Terms of trade is the ratio of export prices to import prices: an improvement allows a country to buy more imports for a given volume of exports.
比较优势（大卫·李嘉图）指出，各国应专业化生产机会成本最低的商品，并通过贸易实现互利，即使一国在所有产品上都具有绝对优势也无妨。其基础是要素禀赋或生产力的差异。贸易条件是指出口价格与进口价格之比：贸易条件的改善使一国能够用给定数量的出口购买更多进口。
Protectionist policies include tariffs, quotas, subsidies, and non-tariff barriers. A tariff raises domestic price, reduces imports, increases domestic producer surplus, but creates deadweight welfare loss. OCR often expects you to contrast protectionism against free trade, considering infant industry, dumping, and national security arguments, while noting the risk of retaliation.
保护主义政策包括关税、配额、补贴和非关税壁垒。关税提高国内价格，减少进口，增加国内生产者剩余，但会造成无谓福利损失。OCR 通常期望你对比保护主义与自由贸易，考虑幼稚产业、倾销和国家安全等论点，同时指出报复的风险。
10. Exchange Rates and External Shocks | 汇率与外部冲击
An exchange rate is the price of one currency in terms of another. Floating rates are determined by demand and supply, influenced by trade flows, interest rate differentials, speculation, and the relative inflation rate. A depreciation makes exports cheaper and imports dearer, boosting net exports (demand-side effect) but also causing imported cost-push inflation.
汇率是一种货币以另一种货币表示的价格。浮动汇率由需求和供给决定，受贸易流、利差、投机和相对通胀率影响。贬值使出口更便宜、进口更昂贵，从而提振净出口（需求侧效应），但同时也会引发进口成本推动型通胀。
Fixed exchange rates require a central bank to intervene by buying or selling reserves to maintain a peg. The Marshall-Lerner condition states that a depreciation will only improve the current account if the sum of the price elasticities of demand for exports and imports is greater than 1. A J-curve effect occurs because in the short run, contracts are fixed, so the trade balance worsens before it improves.
固定汇率要求央行通过买卖外汇储备来维持盯住。马歇尔-勒纳条件指出，只有当出口和进口的需求价格弹性之和大于 1 时，贬值才能改善经常账户。J 曲线效应之所以发生，是因为在短期内合同是固定的，所以贸易余额会先恶化再改善。
11. Financial Markets and the Role of the Central Bank | 金融市场与央行的作用
Financial markets channel funds from savers to borrowers, provide liquidity, price risk, and facilitate speculation. Money markets handle short-term borrowing and lending; capital markets deal with long-term securities like equities and bonds. Market failure in finance arises from asymmetric information (adverse selection, moral hazard), externalities, and systemic risk.
金融市场将资金从储蓄者引导至借款人，提供流动性、为风险定价并促进投机。货币市场处理短期借贷；资本市场则处理股票和债券等长期证券。金融领域的市场失灵源于信息不对称（逆向选择、道德风险）、外部性和系统性风险。
The central bank acts as lender of last resort to prevent liquidity crises, manages the currency, and implements monetary policy to hit the inflation target. Regulation of the financial sector, including capital adequacy ratios and stress tests, aims to maintain financial stability and prevent moral hazard — where banks take excessive risks because they expect to be bailed out.
央行充当最后贷款人以防止流动性危机，管理货币并实施货币政策以达成通胀目标。对金融部门的监管，包括资本充足率和压力测试，旨在维持金融稳定并防止道德风险——即银行因预期会被救助而过度冒险。
12. Supply-Side Policies and Long-Run Growth | 供给侧政策与长期增长
Supply-side policies aim to increase the productive capacity of the economy, shifting LRAS to the right. Market-based policies include tax cuts, deregulation, privatisation, and trade liberalisation to increase incentives and competition. Interventionist policies involve government spending on education, infrastructure, and R&D to improve human capital and technology.
供给侧政策旨在提高经济的生产能力，使 LRAS 向右移动。市场导向的政策包括减税、放松监管、私有化和贸易自由化，以增强激励和竞争。干预主义的政策则涉及政府在教育、基础设施和研发上的支出，以提升人力资本和技术水平。
Policies that shift LRAS can simultaneously raise output and lower inflationary pressure — a win-win scenario. However, time lags, costs, and equity effects (e.g., lower welfare spending freeing up labour but hitting vulnerable groups) provide natural evaluation points for your essays. The long run trend rate of growth is determined by the rate of technological progress, capital accumulation, and labour force growth.
使 LRAS 向右移动的政策可以同时提高产出并降低通胀压力——这是一个双赢的局面。然而，时间滞后、成本以及公平效应（例如，减少福利支出虽能释放劳动力，但会冲击弱势群体）为你的论文提供了天然的评价切入点。长期趋势增长率由技术进步速度、资本积累和劳动力增长决定。
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