Aggregate Demand (AD) · 总需求（AD）
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| aggregate demand/ˈæɡrɪɡeɪt dɪˈmænd/ | 总需求 | zǒng xū qiú |
| wealth effect/welθ ɪˈfekt/ | 财富效应 | cái fù xiào yìng |
| interest rate effect/ˈɪntrest reɪt ɪˈfekt/ | 利率效应 | lì lǜ xiào yìng |
| exchange rate effect/eksˈtʃeɪndʒ reɪt ɪˈfekt/ | 汇率效应 | huì lǜ xiào yìng |
| shift/ʃɪft/ | 移动 | yí dòng |
| consumer confidence/kənˈsuːmə ˈkɒnfɪdəns/ | 消费者信心 | xiāo fèi zhě xìn xīn |
What the whole economy wants to buy
- Unit 2 measured the economy with real GDP and the price level.
- Now we ask what sets those two numbers.
- The first half of the answer is the total demand of everyone at once.
- It is called aggregate demand 总需求 (AD).
整个经济想买什么
- 第二单元用实际 GDP 和价格水平衡量了经济。
- 现在我们问,是什么决定了这两个数字。
- 答案的前一半,是所有人同时的总需求。
- 它叫做总需求(aggregate demand,AD)。
Why AD slopes down
- Aggregate demand is the total real output all buyers want at each price level, and it slopes downward.
- But not for the usual reason — there is no "substitute" for everything. Three economy-wide effects explain it:
- The wealth effect 财富效应: a lower price level makes savings worth more, so people buy more.
- The interest rate effect 利率效应 and exchange rate effect 汇率效应: a lower price level cuts interest rates (lifting investment) and weakens the currency (lifting net exports).
AD 为什么向下倾斜
- 总需求是所有买者在每个价格水平下想要的实际总产出,它向下倾斜。
- 但原因不是通常那个——对所有东西来说没有"替代品"。三个全经济范围的效应解释了它:
- 财富效应(wealth effect):价格水平更低使储蓄更值钱,所以人们买得更多。
- 利率效应(interest rate effect)和汇率效应(exchange rate effect):价格水平更低压低利率(抬升投资)、削弱货币(抬升净出口)。
The AD-AS model · 总需求—总供给模型
Aggregate demand slopes down and shifts right when consumption, investment, government spending, or net exports rise. · 总需求向下倾斜;当消费、投资、政府支出或净出口上升时,它向右移动。
The aggregate demand curve slopes downward mainly because of the wealth, interest rate, and: · 总需求曲线主要因财富、利率和什么效应而向下倾斜:
AD covers every good, so there is no substitution — the three macro effects explain the slope. · AD 涵盖所有商品,没有替代——三个宏观效应解释了斜率。
The wealth effect says a lower price level: · 财富效应说,更低的价格水平:
With a lower price level, the money people already hold buys more, so they feel richer. · 价格水平更低时,人们已持有的钱买得更多,所以感觉更富。
AD's four spending components
- AD is built from the same four parts as GDP: $AD = C + I + G + (X - M)$.
- $C$ consumption, $I$ investment, $G$ government spending, $(X - M)$ net exports.
- A movement along AD happens only when the price level changes.
- A shift 移动 happens when something else changes a component — a rise in any of them shifts AD right.
AD 的四个支出组成部分
- AD 由与 GDP 相同的四个部分构成:$AD = C + I + G + (X - M)$。
- $C$ 消费,$I$ 投资,$G$ 政府支出,$(X - M)$ 净出口。
- 沿曲线移动只在价格水平变化时发生。
- 移位(shift)在别的东西改变某个组成部分时发生——其中任何一个上升都使 AD 右移。
Aggregate demand equals C + I + G + (X − ______). · 总需求等于 C + I + G + (X − ______)。
AD = C + I + G + net exports (X − M). · AD = C + I + G + 净出口 (X − M)。
A rise in consumer confidence causes: · 消费者信心的上升引起:
Higher confidence raises C at every price level, shifting the whole curve right. · 更高的信心在每个价格水平下抬升 C,使整条曲线右移。
A change in the price level causes a movement along AD, not a shift. · 价格水平的变化引起沿 AD 的移动,而不是移位。
Only a change in a spending component shifts AD; the price level moves you along it. · 只有支出组成部分的变化才移动 AD;价格水平让你沿它移动。
What shifts AD
- Consumer confidence 消费者信心 or expected higher incomes raise $C$ → AD right.
- Lower interest rates raise $I$ → AD right.
- Worked idea. A wave of optimism lifts confidence, so households plan 100b more spending at every price level — AD shifts right by 100b (and further once the multiplier acts).
什么会移动 AD
- 消费者信心(consumer confidence)或预期更高的收入抬升 $C$ → AD 右移。
- 更低的利率抬升 $I$ → AD 右移。
- 例题。 一波乐观情绪抬升信心,于是家庭在每个价格水平下计划多花 100 十亿——AD 右移 100 十亿(乘数起作用后还会更多)。
Select all · 所有 that shift AD to the right · 精准的. · 选出所有使 AD 右移的因素。
Higher C, I, or G shift AD right; a price-level change is only a movement along it. · 更高的 C、I 或 G 使 AD 右移;价格水平变化只是沿它移动。
Aggregate demand slopes down via the wealth, interest rate, and exchange rate effects. It is $AD = C + I + G + (X - M)$. The price level moves you along AD; a change in any component shifts it — up shifts AD right, down shifts it left.
总需求通过财富、利率和汇率效应向下倾斜。它是 $AD = C + I + G + (X - M)$。价格水平让你沿 AD 移动;任何组成部分的变化都移动它——上升使 AD 右移,下降使它左移。