AD-AS Model: Key Concepts for GCSE Edexcel Economics | GCSE Edexcel 经济：AD-AS模型考点精讲

📚 AD-AS Model: Key Concepts for GCSE Edexcel Economics | GCSE Edexcel 经济：AD-AS模型考点精讲

Mastering the AD-AS model is essential for GCSE Edexcel Economics. It provides a framework to analyse how changes in aggregate demand and aggregate supply affect the price level, real GDP, employment, and key macroeconomic objectives. This revision guide explains each component, curve, shift, and equilibrium in a straightforward way, helping you build confidence for your exams.

掌握AD-AS模型对于GCSE Edexcel经济学至关重要。这个模型提供了一个框架，用于分析总需求和总供给的变化如何影响价格水平、实际GDP、就业以及关键的宏观经济目标。这份复习指南以简明的方式解释了每一个组成部分、曲线、移动和均衡，帮助你建立考试信心。

1. What Is Aggregate Demand? | 什么是总需求？

Aggregate demand (AD) is the total spending on goods and services in an economy at a given price level over a period of time. It is calculated as: AD = C + I + G + (X – M). Each component represents a major sector of spending.

总需求（AD）是指在一定时期内，在某个既定价格水平下，经济中对商品和服务的总支出。其公式为：AD = C + I + G + (X – M)。每个组成部分都代表一个主要支出部门。

Consumption (C) is household spending on goods and services. It is the largest component in the UK and is influenced by factors such as income, interest rates, and consumer confidence.

消费（C）是家庭对商品和服务的支出，是英国经济中最大的组成部分，受收入、利率和消费者信心等因素影响。

Investment (I) is spending by firms on capital goods, such as machinery, technology, and buildings. It depends on business confidence, interest rates, and expected future profits.

投资（I）是企业对资本品的支出，如机器、技术和建筑，取决于企业信心、利率和预期未来利润。

Government spending (G) covers public services, infrastructure, and welfare payments. It is determined by government policy and is not directly driven by profit motives.

政府支出（G）涵盖公共服务、基础设施和福利支出，由政府政策决定，并非直接由利润动机驱动。

Net exports (X – M) represent the value of exports minus imports. A positive figure adds to AD; a negative figure reduces AD. Exchange rates and global demand are key influences.

净出口（X – M）代表出口额减去进口额。正数增加AD，负数减少AD。汇率和全球需求是其主要影响因素。

2. The AD Curve and Downward Slope | AD曲线及其向下倾斜

The AD curve shows the relationship between the general price level and the quantity of real GDP demanded. It slopes downwards, meaning that as the price level falls, the quantity of real GDP demanded increases.

AD曲线展示了一般价格水平与实际GDP需求量之间的关系。它向右下方倾斜，这意味着当价格水平下降时，实际GDP的需求量会增加。

There are three main reasons for this downward slope:

这种向下倾斜的原因主要有三个：

The wealth effect: A lower price level increases the real value of household wealth, which encourages more consumption.

财富效应：较低的价格水平提高了家庭财富的实际价值，从而鼓励更多消费。

The interest rate effect: When the price level falls, people need less money for transactions, so the demand for money falls. This pushes interest rates down, stimulating investment and consumption.

利率效应：当价格水平下降时，人们交易所需货币减少，货币需求下降，压低了利率，从而刺激投资和消费。

The international trade effect: A lower domestic price level makes UK goods relatively cheaper for foreign buyers, boosting exports, while imports become relatively more expensive, reducing import spending. Net exports rise, increasing AD.

国际贸易效应：较低的国内价格水平使英国商品对外国买家相对更便宜，推动出口，而进口品相对更昂贵，减少进口支出。净出口增加，提升AD。

3. Shifts in Aggregate Demand | 总需求的移动

A change in any component of AD (C, I, G, or X – M) that is not caused by a change in the price level will shift the entire AD curve. An increase in AD shifts the curve to the right; a decrease shifts it to the left.

任何并非由价格水平变化引起的AD组成部分（C、I、G或X – M）的变化，都会导致整个AD曲线移动。AD增加使曲线右移，减少则左移。

Factors that can shift AD right include:

能使AD右移的因素包括：

Lower income tax or higher welfare benefits, raising disposable income and consumption.
降低所得税或提高福利，增加可支配收入和消费。
Cuts in interest rates, making borrowing cheaper and encouraging both consumption and investment.
降息，降低借贷成本，鼓励消费和投资。
Increased business confidence, leading to more investment spending.
企业信心增强，导致更多投资支出。
Expansionary fiscal policy, such as higher government spending on infrastructure.
扩张性财政政策，如增加基础设施政府支出。
A depreciation of the currency, which makes exports cheaper and imports dearer, improving net exports.
货币贬值，使出口更便宜、进口更昂贵，改善净出口。

Similarly, the opposite changes in these factors will shift AD to the left.

同理，这些因素的反向变化将使AD左移。

4. Introducing Aggregate Supply | 总供给简介

Aggregate supply (AS) is the total quantity of goods and services that firms are willing and able to produce in an economy at different price levels. In GCSE, we distinguish between short-run aggregate supply (SRAS) and long-run aggregate supply (LRAS).

总供给（AS）是指在不同价格水平下，经济中的企业愿意并且有能力生产的商品和服务的总量。在GCSE中，我们区分短期总供给（SRAS）和长期总供给（LRAS）。

The SRAS curve assumes that input prices (especially wages) are sticky and do not adjust immediately. The LRAS curve represents the productive potential of the economy when all resources are used efficiently and prices are fully flexible.

SRAS曲线假设要素价格（尤其是工资）具有粘性，无法立即调整。LRAS曲线表示所有资源被有效利用且价格完全弹性时经济的生产潜力。

5. Short-Run Aggregate Supply (SRAS) | 短期总供给（SRAS）

The SRAS curve slopes upwards. As the price level rises, firms are willing to supply more real GDP because their output prices increase relative to input costs in the short run. With sticky wages, a higher price level raises profit margins, motivating firms to expand production.

SRAS曲线向右上方倾斜。随着价格水平上升，由于短期内产出价格相对于投入成本上升，企业愿意提供更多实际GDP。由于工资具有粘性，较高的价格水平提高了利润率，激励企业扩大生产。

The opposite happens when the price level falls: profit margins are squeezed and firms cut back on output. Movements along the SRAS curve are caused solely by changes in the price level.

价格水平下降时则相反：利润率受到挤压，企业减少产出。沿着SRAS曲线的变动仅仅由价格水平的变化引起。

6. Shifts in the SRAS Curve | SRAS曲线的移动

The SRAS curve shifts when there is a change in the costs of production facing firms across the economy. A fall in costs shifts SRAS to the right (increase in supply); a rise in costs shifts SRAS to the left (decrease in supply).

当整个经济中企业面临的生产成本发生变化时，SRAS曲线会发生移动。成本下降使SRAS右移（供给增加），成本上升使其左移（供给减少）。

Key factors shifting SRAS include:

移动SRAS的关键因素包括：

Changes in raw material and energy prices: For example, a rise in oil prices increases production and transport costs, shifting SRAS left.

原材料和能源价格的变化：例如，油价上涨会增加生产和运输成本，使SRAS左移。

Changes in wage rates: An increase in the minimum wage or strong wage growth without a matching rise in productivity raises unit labour costs, shifting SRAS left.

工资率的变化：最低工资上调或工资强劲增长而未伴随生产率相应提高，会增加单位劳动力成本，使SRAS左移。

Changes in indirect taxes or subsidies: A rise in VAT raises firms’ costs, shifting SRAS left. An increase in subsidies reduces costs and shifts SRAS right.

间接税或补贴的变化：增值税提高会增加企业成本，使SRAS左移。补贴增加会降低成本，使SRAS右移。

Supply shocks: Events such as natural disasters or pandemics can reduce productive capacity and raise costs, shifting SRAS left. Improved technology or higher productivity shifts SRAS right.

供给冲击：自然灾害或流行病等事件会降低生产能力并提高成本，使SRAS左移。技术进步或生产率提高会使SRAS右移。

7. Long-Run Aggregate Supply: Classical vs Keynesian | 长期总供给：古典观点与凯恩斯观点

There are two main views of LRAS that you need to know for Edexcel GCSE:

对于Edexcel GCSE，你需要了解两种主要的LRAS观点：

Classical LRAS \| 古典LRAS	Keynesian LRAS \| 凯恩斯LRAS
Vertical line at the full employment level of real GDP. The economy always operates at full capacity in the long run.	Shaped with three sections: horizontal at low output, then upward sloping, then vertical at full employment. Spare capacity can exist.
位于实际GDP的充分就业水平处的一条垂直线。经济在长期总是运行于充分产能。	形状分为三个部分：低产出时水平，然后向上倾斜，最后在充分就业处垂直。可能存在闲置产能。

In the classical model, any increase in AD only raises the price level in the long run (inflation), without increasing real GDP. In the Keynesian model, if there is spare capacity, an increase in AD can raise real GDP without causing inflation.

在古典模型中，AD的任何增加在长期只会推高价格水平（通货膨胀），而不会增加实际GDP。在凯恩斯模型中，如果存在闲置产能，AD的增加可以在不引发通胀的情况下提高实际GDP。

Edexcel typically expects you to use a Keynesian LRAS in analysis, recognising that economies can operate below full employment.

Edexcel通常要求你使用凯恩斯LRAS进行分析，认识到经济可以在低于充分就业的水平运行。

8. Factors Shifting LRAS | 移动LRAS的因素

LRAS shifts when the economy’s productive potential changes. Both classical and Keynesian LRAS can shift right if the quantity or quality of factors of production improves.

当经济的生产潜力发生变化时，LRAS会发生移动。如果生产要素的数量或质量提高，古典和凯恩斯LRAS都可以右移。

Key drivers include:

关键驱动因素包括：

Increase in the quantity of labour: Higher immigration or a rise in the retirement age expands the workforce, shifting LRAS right.

劳动力数量的增加：移民增加或退休年龄提高会扩大劳动力队伍，使LRAS右移。

Improvements in education and training: A more skilled workforce raises labour productivity, boosting potential output.

教育和培训的改善：更高技能的劳动力提高了劳动生产率，从而提升潜在产出。

Investment and technological progress: More and better capital goods, along with innovation, increase the economy’s capacity to produce. This shifts LRAS right.

投资与技术进步：更多更好的资本品以及创新，提高了经济的生产能力，使LRAS右移。

Infrastructure development: Better transport, energy, and digital networks lower costs and improve efficiency, enlarging productive potential.

基础设施发展：更好的交通、能源和数字网络降低成本、提高效率，扩大生产潜力。

Incentives and competition: Supply-side policies like tax reforms or deregulation can encourage enterprise and productivity, shifting LRAS rightward over time.

激励与竞争：供给侧政策如税收改革或放松管制，可以鼓励创业和提高生产率，长期促使LRAS右移。

9. Macroeconomic Equilibrium and Output Gaps | 宏观经济均衡与产出缺口

Macroeconomic equilibrium occurs where AD equals SRAS, determining the current price level and real GDP. When this equilibrium level of real GDP differs from the full employment output shown by LRAS, an output gap exists.

宏观经济均衡发生在AD等于SRAS之处，决定当前的价格水平和实际GDP。当这一均衡实际GDP不同于LRAS所显示的充分就业产出时，就存在产出缺口。

A negative output gap (deflationary gap) occurs when equilibrium real GDP is below the LRAS full employment level. There is spare capacity and high unemployment, putting downward pressure on inflation.

负产出缺口（通货紧缩缺口）发生在均衡实际GDP低于LRAS充分就业水平时。存在闲置产能和高失业，对通胀产生下行压力。

A positive output gap (inflationary gap) occurs when equilibrium real GDP is temporarily above the LRAS full employment level. Resources are over-utilised, unemployment is very low, and demand-pull inflation tends to rise.

正产出缺口（通货膨胀缺口）发生在均衡实际GDP暂时高于LRAS充分就业水平时。资源被过度利用，失业率极低，需求拉动型通胀趋于上升。

In the long run, the economy tends to move towards full employment as wages and prices adjust, but governments may use policies to close these gaps more quickly.

在长期，随着工资和价格的调整，经济趋向于充分就业，但政府可能会使用政策更快地弥合这些缺口。

10. Using AD-AS to Analyse Policy | 用AD-AS分析政策

Policymakers use the AD-AS model to choose between demand-side and supply-side policies. Expansionary fiscal or monetary policy aims to increase AD, shifting it right. Contractionary policy reduces AD.

决策者利用AD-AS模型在需求侧和供给侧政策之间做出选择。扩张性财政或货币政策旨在增加AD，使其右移。紧缩性政策则减少AD。

When an economy has a negative output gap and high unemployment, increasing AD can raise real GDP and lower unemployment without causing much inflation – especially if the LRAS is Keynesian with a flat section.

当经济存在负产出缺口且高失业时，增加AD可以提高实际GDP并降低失业，而不会引发太多通胀——特别是当LRAS为凯恩斯类型且存在平坦部分时。

To combat cost-push inflation (caused by a leftward shift in SRAS), raising AD would only add to inflation. Instead, supply-side policies that shift LRAS or SRAS rightward are more appropriate, as they can lower the price level and increase output.

要应对成本推动型通胀（由SRAS左移引起），增加AD只会加剧通胀。相反，能使LRAS或SRAS右移的供给侧政策更为合适，因为它们可以降低价格水平并提高产出。

Common exam questions ask you to draw and explain how a specific event, such as a rise in government spending or an increase in oil prices, affects the economy. Always label axes (Price Level and Real GDP), draw the initial AD and AS curves, show the shift, and mark the new equilibrium. Then explain the impact on price level, output, and employment.

常见考题要求你画出并解释某个特定事件（如政府支出增加或油价上涨）如何影响经济。始终标注坐标轴（价格水平和实际GDP），画出初始AD与AS曲线，显示移动，并标出新均衡点。然后解释对价格水平、产出和就业的影响。

Demand-pull inflation is shown as a rightward shift of AD when the economy is near full capacity; cost-push inflation is shown as a leftward shift of SRAS, raising the price level and reducing real GDP (stagflation).

需求拉动型通胀表现为当经济接近充分产能时AD右移；成本推动型通胀表现为SRAS左移，推高价格水平并降低实际GDP（滞胀）。

11. Top Exam Tips for AD-AS | AD-AS高分备考贴士

For Edexcel GCSE, always use the AD-AS framework when discussing the whole economy. Keep your diagrams clear and well-labelled. Distinguish between movements along a curve and shifts of the curve – this is a common marker for higher marks.

对于Edexcel GCSE，讨论整体经济时务必使用AD-AS框架。保持图表清晰并做好标注。区分沿着曲线的变动和曲线的移动——这是获取高分的一个常见评分点。

Use precise terminology: ‘aggregate demand’ instead of just ‘demand’, ‘real GDP’ instead of ‘output’, and ‘price level’ instead of ‘inflation’ when describing axes. Reference specific components or factors to show depth of understanding.

使用准确的术语：用 ‘aggregate demand’ 而不仅仅是 ‘demand’，用 ‘real GDP’ 而不是 ‘output’，在描述坐标轴时用 ‘price level’ 而不是 ‘inflation’。提及具体的组成部分或因素以展示理解的深度。

When evaluating policies, consider the context: an economy with lots of spare capacity will respond differently to a demand boost than one at full employment. Recognising the difference between short-run and long-run effects, as well as classical and Keynesian assumptions, can elevate your analysis.

在评估政策时，要考虑背景：存在大量闲置产能的经济对需求刺激的反应，与处于充分就业的经济有所不同。认识到短期影响与长期影响的区别，以及古典和凯恩斯假设的区别，能提升你的分析水平。

Published by TutorHao | Economics Revision Series | aleveler.com

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AD-AS Model: Key Concepts for GCSE Edexcel Economics | GCSE Edexcel 经济：AD-AS模型 考点精讲