The Price System and the Microeconomy | 价格体系与微观经济

📚 The Price System and the Microeconomy | 价格体系与微观经济

The price system is the central mechanism through which microeconomic agents – households, firms and governments – interact in markets. At AS Level, students learn how demand and supply determine prices, how elasticities measure responsiveness, and how government intervention affects market outcomes.

价格体系是微观经济主体——家庭、企业和政府——在市场中互动的核心机制。在AS阶段，学生将学习需求与供给如何决定价格、弹性如何衡量反应程度，以及政府干预如何影响市场结果。

This topic connects individual market decisions to resource allocation. It forms the analytical foundation for understanding efficiency, welfare and the role of government in a microeconomy.

该主题将单个市场决策与资源配置联系起来。它为理解效率、福利以及政府在微观经济中的作用奠定了分析基础。

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1. The Basic Economic Problem and Resource Allocation | 基本经济问题与资源配置

Every economy faces the basic economic problem: unlimited wants but limited resources. This creates scarcity, forcing individuals, firms and governments to make choices that involve opportunity cost – the value of the next best alternative forgone.

每个经济体都面临基本经济问题：欲望无限而资源有限。这造成了稀缺性，迫使个人、企业和政府做出选择，而选择涉及机会成本——所放弃的次优选择的价值。

The price system helps to answer the three key resource allocation questions. Prices act as signals to producers and consumers, provide incentives to reallocate resources, and ration scarce goods among competing uses.

价格体系有助于回答三个关键的资源配置问题。价格作为信号传递给生产者和消费者，为资源再配置提供激励，并在竞争性用途中配给稀缺商品。

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2. Demand: Law, Curve and Determinants | 需求：规律、曲线与决定因素

Demand is the quantity of a good that consumers are willing and able to buy at each price over a given period. The law of demand states that, ceteris paribus, there is an inverse relationship between price and quantity demanded.

需求是指在一定时期内，消费者在各种价格水平上愿意并且能够购买的商品数量。需求规律表明，在其他条件不变的情况下，价格与需求量之间存在反向关系。

This inverse relationship is explained by the substitution effect and the income effect. A fall in price makes the good relatively cheaper, so consumers switch from substitutes, and their real income rises, allowing more purchases.

这种反向关系可以用替代效应和收入效应来解释。价格下降使该商品相对便宜，因此消费者从替代品转向该商品，同时实际收入上升，使购买量增加。

A movement along the demand curve is caused only by a change in the good’s own price. A shift of the curve occurs when any non-price determinant changes, such as income, tastes, prices of substitutes or complements, population and expectations.

沿着需求曲线的移动仅由商品自身价格变化引起。曲线的移动发生在任何非价格决定因素变化时，例如收入、偏好、替代品或互补品价格、人口和预期。

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3. Supply: Law, Curve and Determinants | 供给：规律、曲线与决定因素

Supply is the quantity of a good that producers are willing and able to sell at each price over a given period. The law of supply states that, ceteris paribus, there is a positive relationship between price and quantity supplied.

供给是指在一定时期内，生产者在各种价格水平上愿意并且能够出售的商品数量。供给规律表明，在其他条件不变的情况下，价格与供给量之间存在正向关系。

Higher prices raise potential profit, so existing firms expand output and new firms are attracted into the market. A movement along the supply curve is caused by a change in the good’s own price.

较高的价格提高了潜在利润，因此现有企业扩大产量，新企业被吸引进入市场。沿着供给曲线的移动由商品自身价格变化引起。

Shifts in supply are caused by changes in costs of production, technology, indirect taxes, subsidies, weather conditions, the number of sellers and producer expectations.

供给曲线的移动由生产成本、技术、间接税、补贴、天气条件、卖者数量和生产者预期的变化引起。

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4. Market Equilibrium and the Price Mechanism | 市场均衡与价格机制

Market equilibrium occurs where quantity demanded equals quantity supplied at a particular price. At this price, buyers can purchase exactly the amount they want and sellers can sell exactly the amount they planned.

当某一价格水平上需求量等于供给量时，市场达到均衡。在该价格下，买方能够买到他们想要的准确数量，卖方能够卖出他们计划的准确数量。

If the price is above equilibrium, there is excess supply, so firms cut prices. If the price is below equilibrium, there is excess demand, so buyers bid prices up. These adjustments move the market back to equilibrium.

如果价格高于均衡水平，就会出现超额供给，企业因此降低价格。如果价格低于均衡水平，就会出现超额需求，买方因此抬高价格。这些调整使市场回到均衡。

The price mechanism performs three key functions. Signalling shows where resources are needed; incentives encourage producers and consumers to respond to price changes; rationing allocates scarce goods to those willing and able to pay.

价格机制执行三项关键职能。信号功能显示资源需要流向哪里；激励功能鼓励生产者和消费者对价格变化作出反应；配给功能将稀缺商品分配给愿意且有能力支付的人。

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5. Price Elasticity of Demand (PED) | 需求价格弹性

Price elasticity of demand measures the responsiveness of quantity demanded to a change in the good’s own price. It is calculated as:

需求价格弹性衡量需求量对商品自身价格变化的反应程度。其计算公式为：

PED = %ΔQd ÷ %ΔP

If PED is greater than 1, demand is price elastic; if less than 1, demand is price inelastic; if equal to 1, demand is unit elastic. The sign is negative but economists often ignore the minus sign.

如果PED大于1，需求是富有价格弹性的；如果小于1，需求是缺乏价格弹性的；如果等于1，需求是单位弹性的。该值为负数，但经济学家通常忽略负号。

Key determinants include the availability of close substitutes, the proportion of income spent on the good, whether the good is a necessity or luxury, and the time period considered.

关键决定因素包括相近替代品的可获得性、用于该商品的收入比例、该商品是必需品还是奢侈品，以及所考虑的时间长短。

Total revenue rises when price falls if demand is elastic, and rises when price rises if demand is inelastic. This relationship is important for pricing decisions.

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Published by TutorHao | AS Economics Revision Series | aleveler.com

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