📚 The terms of trade | 贸易条件
The terms of trade measure the rate at which a country's exports exchange for its imports. They capture the relative price of exports compared to imports and serve as a key indicator of a nation's external purchasing power. Movements in the terms of trade affect real incomes, the current account balance, and long‑run growth prospects. For A‑Level Economics, understanding the calculation, determinants, and consequences of terms of trade changes is essential for analysing international trade performance and macroeconomic stability.
贸易条件衡量一国出口商品与进口商品的交换比率，体现了出口相对于进口的价格水平，是反映一国对外购买力的重要指标。贸易条件的变动会影响实际收入、经常账户差额以及长期增长前景。在A‑Level经济课程中，掌握贸易条件的计算、决定因素及其经济后果，对于分析国际贸易表现与宏观经济稳定至关重要。
1. Definition of the Terms of Trade | 贸易条件的定义
The terms of trade (TOT) represent the ratio of export prices to import prices. They indicate how many units of imports can be bought with one unit of exports. When a country's export prices rise relative to its import prices, the terms of trade improve, meaning each exported unit can purchase more imports. Conversely, a decline in export prices relative to import prices implies a deterioration in the terms of trade.
贸易条件（TOT）表示出口价格与进口价格的比率，反映一单位出口能换取多少单位进口。当一国出口价格相对于进口价格上升时，贸易条件改善，意味着每单位出口可以购买更多进口商品。反之，出口价格相对于进口价格下降，则贸易条件恶化。
A favourable terms of trade movement raises the real income of a country, as it can obtain a larger volume of imports for a given volume of exports. However, an improvement is not automatically beneficial if it results from falling competitiveness or if it triggers a decline in export volumes. The net effect on the trade balance depends on the price elasticities of demand for exports and imports.
贸易条件的有利变动会提高一国的实际收入，因为在既定出口数量下能够获得更多的进口商品。然而，若这种改善源于竞争力下降或导致出口数量急剧萎缩，则并非必然有利。对贸易差额的净影响取决于出口和进口需求的价格弹性。
2. Measuring the Terms of Trade | 贸易条件的衡量
The most common measure is the commodity terms of trade, also known as the net barter terms of trade. It is calculated as an index:
Terms of Trade Index = (Export Price Index ÷ Import Price Index) × 100
A value above 100 indicates that export prices have risen faster than import prices since the base year, signalling an improvement. A value below 100 suggests a deterioration. Economists also employ the income terms of trade, which adjust the commodity terms of trade by the volume of exports, showing the import purchasing power of total export earnings.
最常见的衡量指标是商品贸易条件，也称净易货贸易条件，其计算公式为指数：
贸易条件指数 = (出口价格指数 ÷ 进口价格指数) × 100
数值高于100表明自基年以来出口价格涨幅超过进口价格，即贸易条件改善；低于100则表示恶化。经济学家也会使用收入贸易条件，即用出口数量对商品贸易条件进行调整，以显示总出口收入的进口购买力。
For example, if a country' 100 to 110, the terms of trade index improves from 100 to (120/110)×100 ≈ 109.1. This 9.1% improvement means the country can now import 9.1% more goods for the same physical quantity of exports.
例如，若某国出口价格指数从100升至120，而进口价格指数从100升至110，则贸易条件指数从100改善至(120/110)×100≈109.1。这9.1%的改善意味着在出口实物量不变的情况下，该国可多进口9.1%的商品。
3. Interpreting Improvements and Deteriorations | 贸易条件升降的解读
An improvement in the terms of trade typically raises domestic living standards, as consumers can enjoy more imports without increasing export effort. However, it can also reflect a loss of international competitiveness if export prices are forced up by domestic cost‑push inflation. In such cases, export demand may collapse, worsening the current account despite the better TOT ratio.
贸易条件改善通常会提高国内生活水平，因为消费者无需增加出口量即可享受更多进口商品。但这也可能反映出国际竞争力下降，如果贸易条件改善是由国内成本推动型通胀推高出口价格所致。此时，尽管贸易条件比率好转，出口需求可能骤降，导致经常账户恶化。
A deterioration in the terms of trade often hits real incomes, as the country must sell more exports to pay for the same basket of imports. Yet a deliberate depreciation of the exchange rate can worsen the TOT while simultaneously boosting export volumes and reducing import penetration. The overall impact depends on whether the Marshall‑Lerner condition holds, i.e. whether the sum of price elasticities of demand for exports and imports exceeds unity.
贸易条件恶化通常损害实际收入，因为国家需要出售更多出口商品才能换取同等数量的进口商品。然而，刻意让货币贬值虽会恶化贸易条件，却也能同时扩大出口量和降低进口渗透率。整体影响取决于马歇尔‑勒纳条件是否成立，即出口与进口需求的价格弹性之和大于1。
Short‑run and long‑run elasticities may differ. In the very short run, trade volumes are often inelastic, so a TOT deterioration can worsen the trade balance (the J‑curve effect) before an eventual improvement if the Marshall‑Lerner condition is satisfied.
短期与长期弹性可能不同。在极短期内，贸易数量往往缺乏弹性，因此贸易条件恶化可能先加剧贸易逆差（J曲线效应），随后若满足马歇尔‑勒纳条件，贸易差额才会改善。
4. Key Determinant: Relative Inflation Rates | 关键决定因素：相对通胀率
Countries with persistently lower inflation rates than their trading partners tend to experience an improving terms of trade. Low inflation keeps export prices competitive while import prices may rise faster if the country is a price taker in global markets. Conversely, high domestic inflation erodes the terms of trade by pushing up export prices faster than import prices, unless offset by a depreciating currency.
与贸易伙伴相比通货膨胀率持续较低的国家，贸易条件往往趋于改善。低通胀使得出口价格保持竞争力，而作为全球市场价格接受者，进口价格可能上涨更快。相反，国内高通胀会通过令出口价格上涨快于进口价格而侵蚀贸易条件，除非本币贬值予以抵消。
Relative inflation also operates through its effect on real exchange rates. If a country's inflation exceeds that of its competitors, its real effective exchange rate appreciates even if the nominal rate is fixed. This erodes export competitiveness and worsens the terms of trade, as export prices must be cut to maintain market share.
相对通胀也通过实际汇率产生作用。如果一国通胀高于竞争对手，即使名义汇率固定，实际有效汇率也会升值。这会削弱出口竞争力并恶化贸易条件，因为为维持市场份额，出口价格不得不下调。
5. Key Determinant: Exchange Rate Movements | 关键决定因素：汇率变动
A depreciation of the domestic currency directly worsens the commodity terms of trade because export prices fall in foreign currency terms while import prices rise in domestic currency. However, this deterioration can stimulate net exports if volumes respond sufficiently. An appreciation improves the TOT by raising the foreign‑currency price of exports and lowering the domestic‑currency price of imports, but at the risk of harming export‑oriented sectors.
本币贬值直接恶化商品贸易条件，因为以外国货币计价的出口价格下跌，而以本币计价的进口价格上升。但这种恶化在出口和进口数量充分响应的情况下可以刺激净出口。货币升值则通过提高出口的外币价格并降低进口的本币价格来改善贸易条件，但有可能损害出口导向型部门。
Managed float systems allow countries to influence the TOT through intervention. For instance, a central bank may buy foreign reserves to prevent excessive appreciation and protect the terms of trade from rising too rapidly, which could harm export industries in the long run.
在管理浮动汇率制度下，各国可通过干预来影响贸易条件。例如，央行可能买入外汇储备以防止本币过度升值，避免贸易条件过快上升而长期损害出口产业。
6. Key Determinant: Productivity and Income Growth | 关键决定因素：生产率与收入增长
Rapid productivity growth in the tradable sector allows a country to lower export prices without squeezing profits, potentially improving the quantity of exports sold while the terms of trade may move in either direction depending on global demand. If the country has monopoly power in certain high‑tech goods, productivity gains can raise real incomes and improve the terms of trade simultaneously.
可贸易部门生产率的快速提升使一国在不压缩利润的情况下降低出口价格，从而可能扩大出口量；而贸易条件的走向则取决于全球需求。如果国家在某些高技术产品上拥有垄断力量，生产率的提高可以同时增加实际收入并改善贸易条件。
On the other hand, rising national income typically boosts import demand. If import demand is income‑elastic, higher GDP can raise import volumes and, if foreign suppliers raise prices, worsen the terms of trade through increased import prices. This effect is particularly relevant for rapidly growing emerging economies that rely heavily on imported capital goods and energy.
另一方面，国民收入上升通常会增加进口需求。如果进口需求的收入弹性较大，GDP增长将推高进口量；若外国供应商借机提价，进口价格上升便会恶化贸易条件。这对于依赖进口资本品和能源的快速增长的新兴经济体尤其重要。
7. Key Determinant: Global Demand Shifts and Commodity Prices | 关键决定因素：全球需求变动与大宗商品价格
Countries that specialise in primary commodities often face volatile terms of trade because commodity prices are subject to large swings in global demand and supply. A surge in global infrastructure spending lifts prices of metals and energy, improving the terms of trade for exporters of those commodities. A global recession has the opposite effect, squeezing export revenues and worsening the TOT for commodity‑dependent economies.
专门从事初级产品出口的国家通常面临波动剧烈的贸易条件，因为大宗商品价格极易受全球供需冲击。全球基建支出的激增会推高金属和能源价格，改善这些商品出口国的贸易条件；而全球经济衰退则会产生相反效果，压缩出口收入并在依赖初级产品出口的经济体中恶化贸易条件。
For manufactured goods exporters, terms of trade are often more stable because of diversified export baskets and relatively inelastic global demand for many consumer goods. Nevertheless, technological shifts, such as the relocation of supply chains, can still cause long‑term terms of trade changes.
对于制成品出口国，由于出口篮子多样化和多种消费品全球需求相对缺乏弹性，贸易条件往往更为稳定。不过，供应链迁移等技术变迁仍可能引发长期的贸易条件变化。
8. The Prebisch‑Singer Hypothesis | 普雷维什‑辛格假说
The Prebisch‑Singer thesis argues that there is a long‑run tendency for the terms of trade of primary‑commodity‑exporting developing countries to deteriorate relative to those of manufactured‑goods‑exporting developed countries. The reasons include low income elasticity of demand for agricultural products, substitution by synthetics, and the market power of multinational firms that compress commodity prices.
普雷维什‑辛格命题认为，从长期看，出口初级产品的发展中国家的贸易条件相对于出口制成品的发达国家有不断恶化的趋势。原因包括农产品需求的收入弹性低、合成材料的替代作用，以及跨国公司压低价位所体现的市场势力。
If true, this hypothesis implies that developing economies need to diversify into manufacturing and services in order to escape a secular decline in purchasing power. Many rapidly industrialising Asian economies have indeed seen their terms of trade stabilise or improve after moving up the value chain, lending partial support to the hypothesis.
该假说若成立，意味着发展中经济体需要通过多元化转向制造业和服务业，以摆脱购买力的长期下降。许多快速工业化的亚洲经济体在价值链上移后，贸易条件确实趋于稳定甚至改善，为这一假说提供了部分支持。
9. Terms of Trade and the Current Account | 贸易条件与经常账户
A change in the terms of trade has an unambiguous effect on the trade balance only if the price elasticities of demand for exports and imports are known. A terms‑of‑trade improvement reduces the quantity of exports that can be sold at a higher price while making imports more attractive. The current account will improve only if the positive price effect outweighs the negative volume effect.
只有知道出口和进口需求的价格弹性，才能明确贸易条件变动对贸易差额的影响。贸易条件改善会降低较高价格下可售出的出口数量，同时让进口更具吸引力。只有当正面的价格效应超过负面的数量效应时，经常账户才会改善。
The combined price elasticities analysis is central to AS/A‑Level answers. If the sum of export and import price elasticities is greater than one (the Marshall‑Lerner condition), a deterioration in the terms of trade (e.g. through depreciation) will, after a time lag, improve the current account. If the sum is less than one, a TOT worsening may further damage the balance.
价格弹性的综合分析是A‑Level答题的核心。若出口和进口价格弹性之和大于1（满足马歇尔‑勒纳条件），贸易条件恶化（如通过贬值）在经过一段时滞后将改善经常账户。若之和小于1，贸易条件恶化则可能进一步损害收支差额。
10. Impact on Economic Growth and Living Standards | 对经济增长和生活水平的影响
Favourable terms of trade can boost domestic welfare by increasing the real purchasing power of national income. Consumers gain access to cheaper imports and a wider variety of goods. Governments may also collect more tariff revenue if import volumes rise on the back of stronger purchasing power. However, persistent improvement might indicate falling competitiveness in high‑value industries, threatening long‑term growth.
有利的贸易条件通过提高国民收入的实际购买力来提升国内福利。消费者可以享受到更便宜的进口商品和更多样的产品。若进口量随购买力增强而上升，政府也可能获得更多关税收入。然而，贸易条件的持续改善可能意味着高附加值产业竞争力下降，对长期增长构成威胁。
Conversely, a sustained deterioration in the terms of trade erodes real incomes, especially for low‑income households that depend heavily on imported food and fuel. Governments may face pressure to introduce subsidies or tighten monetary policy, potentially slowing investment and growth.
相反，贸易条件的持续恶化会侵蚀实际收入，尤其对严重依赖进口食品与燃料的低收入家庭影响显著。政府可能被迫发放补贴或收紧货币政策，从而抑制投资与经济增长。
11. Policy Responses to Terms of Trade Changes | 应对贸易条件变化的政策
When the terms of trade deteriorate sharply, a government might allow the currency to float lower to regain competitiveness, provided inflation is under control. Supply‑side policies, such as investment in education and infrastructure, can help shift the production structure towards higher‑value exports, thereby improving the terms of trade in the long run.
当贸易条件急剧恶化时，政府可在通胀受控的前提下让货币小幅贬值，以重获竞争力。供给侧政策，如投资教育与基础设施，有助于将生产结构转向高附加值出口，从而长期改善贸易条件。
Countries facing a terms‑of‑trade boom from a commodity price spike may establish sovereign wealth funds to sterilise the influx of foreign exchange and avoid Dutch disease. By saving windfall revenues, they can insulate the real exchange rate from excessive appreciation, safeguarding the competitiveness of non‑commodity tradable sectors.
因大宗商品价格飙升而迎来贸易条件繁荣的国家可设立主权财富基金，冲销外汇流入并防止“荷兰病”。通过储蓄暴利收入，可避免实际汇率过度升值，保护非大宗商品可贸易部门的竞争力。
12. Conclusion | 结论
The terms of trade provide a crucial lens through which to view a country's international economic position. Their calculation is straightforward, but the drivers—relative inflation, exchange rates, productivity, and global demand—are complex and interrelated. While an improvement seems desirable, it must be assessed alongside competitiveness and trade elasticities. For A‑Level candidates, linking terms of trade changes to the current account, Marshall‑Lerner condition, and long‑run growth provides a rigorous analytical framework for exam success.
贸易条件提供了一个审视一国国际经济地位的重要窗口。其计算虽简单，但驱动因素——相对通胀、汇率、生产率及全球需求——却复杂且相互关联。尽管改善看似有利，但必须结合竞争力与贸易弹性加以评判。对A‑Level考生而言，将贸易条件变化与经常账户、马歇尔‑勒纳条件及长期增长相联结，构成了实现考试成功的严谨分析框架。
Published by TutorHao | Economics Revision Series | aleveler.com
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