Price elasticity of demand · 需求价格弹性
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| price elasticity of demand/praɪs ɪlæˈstɪsɪti ɒv dɪˈmænd/ | 需求价格弹性 | xū qiú jià gé tán xìng |
| revenue/ˈrevənjuː/ | 营业收入 | yíng yè shōu rù |
| elastic/ɪˈlæstɪk/ | 富有弹性 | fù yǒu tán xìng |
| inelastic/ɪnɪˈlæstɪk/ | 缺乏弹性 | quē fá tán xìng |
| substitutes/ˈsʌbstɪtjuːts/ | 替代品 | tì dài pǐn |
| necessity/nəˈsesɪti/ | 必需品 | bì xū pǐn |
| luxury/ˈlʌkʃəri/ | 奢侈品 | shē chǐ pǐn |
Why petrol prices can soar without denting sales
- Double the price of a designer handbag and sales collapse. Double the price of petrol and people grumble but keep buying.
- Price elasticity of demand 需求价格弹性 (PED) measures exactly how sensitive buyers are — and it decides what happens to a firm's revenue 营业收入.
为什么汽油价格能飙升而不损害销量
- 把一个名牌手袋的价格翻倍,销量就崩溃。把汽油的价格翻倍,人们抱怨但继续买。
- 需求价格弹性(price elasticity of demand,PED)精确地测量买家有多敏感——而它决定一个企业的收入会发生什么。
Measuring PED
- PED measures the responsiveness of quantity demanded to a price change:
- It is usually negative (price and quantity move opposite ways); we focus on its size.
In a market, buyers and sellers meet and the price settles where demand equals supply
测量 PED
- PED 测量需求量对一个价格变化的反应性:
- 它通常是负的(价格和数量反向移动);我们关注它的大小。
在一个市场里,买家和卖家相遇,价格在需求等于供给的地方稳定下来
Demand & supply · 需求与供给
Elasticity is the steepness of demand — flatter means more responsive. · 弹性是需求的陡度——更平意味着更有反应。
Demand is described as elastic when the size of PED is: · 当 PED 的大小是以下时,需求被描述为弹性的:
|PED| > 1 is elastic (quantity is very responsive); |PED| < 1 is inelastic. · |PED| > 1 是弹性的(数量非常有反应);|PED| < 1 是非弹性的。
PED = (% change in quantity demanded) ÷ (% change in ______). · PED =(需求量的 % 变化)÷(______的 % 变化)。
PED divides the % change in quantity demanded by the % change in price. · PED 把需求量的 % 变化除以价格的 % 变化。
Elastic 富有弹性 vs inelastic 缺乏弹性
- $|\text{PED}| > 1$ → elastic (quantity is very responsive — luxuries, many substitutes 替代品).
- $|\text{PED}| < 1$ → inelastic (quantity barely responds — necessities, few substitutes).
A steep curve is inelastic; a flat curve is elastic. The flatter the curve, the more buyers respond.
Worked example. Price rises 20% and quantity demanded falls 10%. PED $= \dfrac{-10\%}{+20\%} = -0.5$ — inelastic (size < 1).
A rise in demand raises both equilibrium price and quantity
弹性对非弹性
- $|\text{PED}| > 1$ → 弹性(elastic,数量非常有反应——奢侈品、许多替代品)。
- $|\text{PED}| < 1$ → 非弹性(inelastic,数量几乎不反应——必需品、很少替代品)。
一条陡的曲线是非弹性的;一条平的曲线是弹性的。曲线越平,买家反应越多。
算例。 价格上升 20% 而需求量下降 10%。PED $= \dfrac{-10\%}{+20\%} = -0.5$——非弹性(大小 < 1)。
需求的上升同时提高均衡价格和数量
Price rises 20% and quantity demanded falls 10%. What is the PED (as a decimal, keep the sign)? · 价格上升 20% 而需求量下降 10%。PED 是多少(作为一个小数,保留符号)?
PED = −10% / +20% = −0.5 (inelastic). · PED = −10% / +20% = −0.5(非弹性)。
PED and revenue
- The link firms care about: if demand is inelastic, raising price raises total revenue; if elastic, raising price lowers revenue.
- Determinants of PED: substitutes (more → more elastic), whether it's a necessity 必需品 or luxury 奢侈品, and the time period (more elastic over time).
Petrol has price-inelastic demand: drivers must buy it, so a price rise cuts the quantity bought only a little
PED 与收入
- 企业关心的联系:如果需求非弹性,提高价格提高总收入;如果弹性,提高价格降低收入。
- PED 的决定因素:替代品(更多 → 更有弹性)、它是必需品还是奢侈品,以及时间期(随时间更有弹性)。
汽油有价格非弹性的需求:司机必须买它,所以一次价格上升只略微减少买的数量
If demand is inelastic, a firm that raises its price will find total revenue: · 如果需求非弹性,一个提高价格的企业会发现总收入:
Inelastic: quantity barely falls, so the higher price raises revenue. · 非弹性:数量几乎不下降,所以更高的价格提高收入。
Necessities with few substitutes tend to have inelastic demand. · 替代品很少的必需品倾向于有非弹性的需求。
People keep buying necessities even when the price rises → inelastic. · 即使价格上升,人们也继续买必需品 → 非弹性。
You've got it
- $\text{PED} = \dfrac{\%\Delta Q_d}{\%\Delta P}$ — focus on the size
- $|\text{PED}|>1$ elastic (flat curve); $|\text{PED}|<1$ inelastic (steep curve)
- inelastic → raise price to raise revenue; elastic → raising price cuts revenue
你掌握了
- $\text{PED} = \dfrac{\%\Delta Q_d}{\%\Delta P}$——关注大小
- $|\text{PED}|>1$ 弹性(平曲线);$|\text{PED}|<1$ 非弹性(陡曲线)
- 非弹性 → 提高价格来提高收入;弹性 → 提高价格减少收入