📚 Classification of Goods and Services | 商品与服务的分类方法
Economists classify goods and services in several different ways. Each classification helps us understand how markets work, why some goods are provided by the state, and how consumers and firms respond to changes in income and prices.
经济学家从不同角度对商品与服务进行分类。每一种分类方法都能帮助我们理解市场如何运作、为什么某些商品由政府提供，以及消费者与企业如何对收入和价格的变化作出反应。
1. Why Classification Matters | 为什么要分类
Classification is not just a theoretical exercise. It allows economists to predict the behaviour of markets, design appropriate government policies, and explain real-world problems such as pollution, under-provision of education, and over-consumption of cigarettes.
分类并不仅仅是一种理论操练。它让经济学家能够预测市场行为、设计合理的政府政策，并解释现实中的问题，例如污染、教育供给不足以及香烟的过度消费。
Goods and services can be classified by scarcity, rivalry, excludability, income elasticity, and the presence of externalities. Each criterion gives a different insight into how a product should be treated by the market and by the state.
商品与服务可以按照稀缺性、竞争性、排他性、收入弹性以及外部性来分类。每一项标准都能提供不同视角，帮助我们理解某类产品应如何由市场和政府来对待。
2. Free Goods and Economic Goods | 自由物品与经济物品
A free good is available in unlimited supply at zero opportunity cost. Examples include sunshine, fresh air, and sea water. Because there is no scarcity, people do not need to pay for free goods, and no market is required to allocate them.
自由物品是指供给无限、机会成本为零的物品。阳光、新鲜空气和海水都是例子。由于没有稀缺性，人们无需为自由物品付费，也不需要市场来配置它们。
An economic good is scarce and therefore has an opportunity cost. Most goods people buy, such as food, clothing, and mobile phones, are economic goods. Producing more of an economic good means sacrificing the production of something else.
经济物品是稀缺的，因此具有机会成本。人们购买的大多数商品，如食物、衣服和手机，都是经济物品。多生产一种经济物品，就意味着要放弃其他产品的生产。
3. Private Goods | 私人物品
A private good has two main characteristics: rivalry and excludability. Rivalry means that one person’s consumption reduces the amount available for others. Excludability means that the seller can prevent a non-buyer from using the good. An apple is a typical private good: if one person eats it, no one else can, and the seller can refuse to give it to someone who does not pay.
私人物品有两个主要特征：竞争性和排他性。竞争性指一个人消费会减少他人可获得的量；排他性指卖方能够阻止未付款者使用该物品。苹果是典型的私人物品：如果一个人吃了它，其他人就不能吃，卖方也可以拒绝将苹果给予不付款的人。
Private goods are usually produced efficiently by markets. Prices act as a rationing mechanism, and firms have strong incentives to supply goods that consumers are willing to pay for.
私人物品通常由市场有效率地生产。价格发挥配给作用，企业也有很强的动机去供应消费者愿意付费的商品。
4. Public Goods | 公共物品
A public good is both non-rival and non-excludable. Non-rival means that one person’s consumption does not reduce the amount available for others. Non-excludable means that it is impossible or very costly to stop someone who has not paid from using the good. National defence and street lighting are classic examples.
公共物品同时具有非竞争性和非排他性。非竞争性意味着一个人消费不会减少他人可获得的量；非排他性意味着要阻止未付费者使用该物品是不可能的，或者代价极高。国防和路灯是典型例子。
Because public goods are non-excludable, consumers can become free riders: they enjoy the benefits without paying. As a result, private firms are unlikely to supply enough public goods. Governments therefore often provide them directly and finance them through taxation.
由于公共物品具有非排他性，消费者可能成为“搭便车者”：不支付费用却享受好处。因此，私人企业不太可能提供足够的公共物品。政府通常会直接提供公共物品，并通过税收来融资。
5. The Four-Way Classification by Rivalry and Excludability | 根据竞争性与排他性的四种分类
Goods can be placed into four categories depending on whether they are rival and excludable. This framework is useful for analysing market failure and government intervention.
根据商品是否具有竞争性和排他性，可以将商品分为四类。这一分析框架有助于分析市场失灵和政府干预。
| Excludable 排他 |
Non-excludable 非排他 |
|
| Rival 竞争 |
Private goods 私人物品 (e.g. food, clothing) |
Common pool resources 公共池塘资源 (e.g. fish stocks, woodlands) |
| Non-rival 非竞争 |
Club goods 俱乐部物品 (e.g. cinema, cable TV, gyms) |
Public goods 公共物品 (e.g. national defence, street lighting) |
Common pool resources are rival but non-excludable. They are often over-used because people do not have to pay to use them. This is known as the tragedy of the commons. Club goods are non-rival but excludable, such as a subscription to an online streaming service.
公共池塘资源具有竞争性但不具有排他性。因为无需付费即可使用，它们常常被过度使用，这被称为“公地悲剧”。俱乐部物品则具有非竞争性但具有排他性，例如在线流媒体服务的订阅。
6. Merit Goods | 优良品
Merit goods are goods that society believes people will under-consume if left to the free market. They generate positive externalities, meaning that the social benefit is greater than the private benefit. Education and vaccinations are the most common examples.
优良品是指社会认为如果完全依赖自由市场，人们会消费不足的商品。优良品会产生正外部性，也就是说社会收益大于私人收益。教育和疫苗接种是最常见的例子。
Consumers often have imperfect information about the long-term benefits of merit goods. For example, a student may not fully realise how much higher lifetime earnings are associated with more education. Governments may subsidise merit goods or provide them free of charge to encourage consumption.
消费者通常对优良品的长期收益信息掌握不充分。例如，学生可能并未充分意识到更多教育会带来更高的终身收入。政府可能会补贴优良品，或免费提供它们，以鼓励消费。
7. Demerit Goods | 不良品
Demerit goods are goods that society believes people will over-consume because they create negative externalities. The private benefit to the user is larger than the social benefit, and consumers may be unable to assess the true costs of their habits. Cigarettes, alcohol, and gambling are typical demerit goods.
不良品是指社会认为人们会过度消费、并带来负外部性的商品。使用者获得的私人收益大于社会收益，而且消费者可能无法准确评估自己行为的真实成本。香烟、酒精和赌博是典型的不良品。
Governments often use indirect taxes, advertising bans, age restrictions, and minimum pricing to reduce the consumption of demerit goods. These policies aim to correct the market failure caused by negative externalities.
政府通常使用间接税、广告禁令、年龄限制和最低价格政策来减少不良品的消费。这些政策旨在纠正由负外部性导致的市场失灵。
8. Normal Goods and Inferior Goods | 正常品与低档品
Goods can also be classified according to how demand changes when income changes. This is measured by income elasticity of demand (YED):
商品还可以根据需求如何随收入变化来分类，这由需求的收入弹性（YED）来衡量：
YED = % change in quantity demanded ÷ % change in income
For a normal good, YED is positive. As income rises, demand also rises. Necessities have a YED between 0 and 1, such as basic food or utilities, meaning demand rises less than proportionally. Luxuries have a YED greater than 1, such as foreign holidays and designer clothing, meaning demand rises more than proportionally.
对于正常品，YED为正。收入上升，需求也上升。必需品的YED介于0和1之间，例如基本食物或水电，意味着需求的增幅小于收入的增幅。奢侈品（如国外度假和名牌服装）的YED大于1，意味着需求的增幅超过收入的增幅。
An inferior good has a negative YED. When income rises, consumers buy less of it. Examples include cheap instant noodles, second-hand furniture, and low-quality bus services. As people become richer, they switch to better alternatives.
低档品的YED为负。当收入上升时，消费者会减少购买这类商品。例子包括廉价方便面、二手家具和低质量的公交服务。随着人们变富，他们会转向更好的替代品。
9. Consumer Goods and Capital Goods | 消费品与资本品
Consumer goods are bought by households for final consumption and directly satisfy wants. They include food, clothing, television sets, and haircuts. Capital goods are produced to be used in the production of other goods and services, such as machinery, factory buildings, and computers used by businesses.
消费品由家庭购买用于最终消费，直接满足需要。它们包括食物、衣服、电视机和理发服务。资本品则是用来生产其他商品与服务的物品，例如机器、厂房和企业使用的电脑。
The distinction is important because capital goods affect a country’s future productive capacity. When economies invest in capital goods, they sacrifice current consumption in order to produce more goods and services in the future.
这种区分很重要，因为资本品影响一个国家未来的生产能力。当经济体投资于资本品时，它们牺牲当前消费，以便未来生产更多的商品与服务。
10. Final Goods and Intermediate Goods | 最终物品与中间物品
A final good is sold to its final user and is not used up in further production. A loaf of bread sold to a household is a final good. An intermediate good is used as an input in the production of another good, such as flour bought by a bakery.
最终物品是指出售给最终使用者、不再用于进一步生产的物品。卖给家庭的面包是最终物品。中间物品则用作生产另一种物品的投入，例如面包店购买的面粉。
Economists must distinguish between final and intermediate goods when measuring national income. Counting both the flour and the bread would result in double counting. Only the value of final goods should be included in GDP.
经济学家在衡量国民收入时必须区分最终物品与中间物品。如果把面粉和面包都计入，就会出现重复计算。国内生产总值中只应计入最终物品的价值。
11. Complementary Goods and Substitute Goods | 互补品与替代品
Goods can also be classified by their relationship in consumption. Complementary goods are used together, such as printers and ink cartridges, or cars and petrol. Substitute goods can replace each other, such as tea and coffee, or butter and margarine.
商品还可以根据消费中的关系来分类。互补品是搭配使用的商品，例如打印机与墨盒、汽车与汽油。替代品则能互相替换，例如茶与咖啡、黄油与人造黄油。
The cross elasticity of demand describes how strongly these relationships work. For complements, the cross elasticity is negative: an increase in the price of one good leads to a fall in demand for the other. For substitutes, the cross elasticity is positive: an increase in the price of one good leads to a rise in demand for the other.
需求的交叉弹性描述了这些关系的强弱。互补品的交叉弹性为负：一种商品价格上升会导致另一种商品需求下降。替代品的交叉弹性为正：一种商品价格上升会导致另一种商品需求上升。
Overall, the classification of goods and services is a powerful tool in economics. By applying different criteria, economists and policymakers can identify market failures, decide whether government intervention is needed, and understand how consumers react to changes in income and prices.
总的来说，商品与服务的分类是经济学中一个强有力的工具。通过运用不同标准，经济学家和政策制定者能够识别市场失灵、判断是否需要政府干预，并理解消费者如何对收入和价格的变化作出反应。
Published by TutorHao | Economics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导