📚 Terms of Trade: Meaning and Calculation | 贸易条件：含义与计算解析
In international economics, the terms of trade are a key indicator of a country's trading position. They measure the relative price of a country's exports in terms of its imports.
在国际经济学中，贸易条件是衡量一国贸易地位的关键指标。它衡量一国出口品相对于进口品的价格水平。
1. What Are Terms of Trade? | 什么是贸易条件
In international trade, the terms of trade (often abbreviated as TOT) compare the prices a country receives for its exports with the prices it must pay for its imports. They are measured as an index number.
在国际贸易中，贸易条件（常缩写为 TOT）比较一国出口所获得的价格与其进口所必须支付的价格。它通常以指数形式来衡量。
A country's terms of trade are said to improve when export prices rise relative to import prices. They deteriorate when export prices fall relative to import prices.
当出口价格相对于进口价格上升时，该国的贸易条件改善；当出口价格相对于进口价格下降时，贸易条件恶化。
2. The Formula | 计算公式
The standard formula used in CIE A-Level Economics is:
CIE A-Level 经济学所使用的标准公式是：
Terms of Trade = (Index of Average Export Prices ÷ Index of Average Import Prices) × 100
贸易条件 =（平均出口价格指数 ÷ 平均进口价格指数）× 100
In this formula, the numerator is the export price index and the denominator is the import price index. Both are index numbers with the same base year, usually set to 100.
在这个公式中，分子是出口价格指数，分母是进口价格指数。两者均使用同一基年，通常基年数值设定为 100。
Multiplying by 100 turns the ratio into an index. A value of 100 means export and import prices have changed by the same proportion since the base year.
乘以 100 将比值转换为指数。数值为 100 意味着自基年以来出口价格与进口价格变动比例相同。
3. Price Indices Explained | 价格指数解析
An index number is a dimensionless measure that shows changes in a variable relative to a base period. For example, if the base year is 2018, the index is 100 in that year. If average export prices rise by 10%, the export price index becomes 110.
指数是一个无量纲数据，用于表示变量相对于基期的变化。例如，若基年为 2018 年，则该年指数为 100。如果平均出口价格上涨 10%，出口价格指数就变为 110。
In practice, countries export and import many different goods. Statisticians therefore use a weighted average of prices, with weights based on the relative importance of each good in a country's trade.
实际上，一国进出口许多不同商品。统计部门因而使用价格的加权平均值，权重取决于每种商品在一国贸易中的相对重要性。
It is essential that the export and import price indices use the same base year and similar weighting systems, otherwise the terms of trade calculation will be unreliable.
出口和进口价格指数必须使用相同基年和相近的权重体系，否则贸易条件的计算结果将不可靠。
4. Worked Calculation | 计算示例
Assume the following data for a country, with 2018 as the base year:
假设某国数据如下，以 2018 年为基年：
| Year | Export Price Index | Import Price Index | Terms of Trade |
|---|---|---|---|
| 2018 | 100 | 100 | 100.0 |
| 2019 | 108 | 105 | 102.9 |
| 2020 | 115 | 120 | 95.8 |
is an improvement compared with 100, because export prices rose faster than import prices.
2019 年的贸易条件为 (108 ÷ 105) × 100 = 102.9。与 100 相比，这是改善，因为出口价格的上涨快于进口价格。
100 = 95.8. This is a deterioration, because import prices rose faster than export prices.
2020 年的贸易条件为 (115 ÷ 120) × 100 = 95.8。这是恶化，因为进口价格的上涨快于出口价格。
Notice that the terms of trade can move above or below 100 depending on whether export prices grow faster or slower than import prices.
注意，贸易条件可能高于或低于 100，取决于出口价格增速是否快于进口价格增速。
5. What Does an Improvement Mean? | 贸易条件改善的含义
An improvement in the terms of trade means that a unit of exports can now purchase more imports than before. For example, if oil prices rise, an oil-exporting country's export price index increases and its terms of trade improve.
贸易条件改善意味着每一单位出口现在可以换取比以前更多的进口品。
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