Marginal Analysis and Consumer Choice · 边际分析与消费者选择
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| margin/ˈmɑːdʒɪn/ | 边际 | biān jì |
| marginal benefit/ˈmɑːdʒɪnl ˈbenɪfɪt/ | 边际收益 | biān jì shōu yì |
| marginal cost/ˈmɑːdʒɪnl kɒst/ | 边际成本 | biān jì chéng běn |
| utility/juːˈtɪlɪti/ | 效用 | xiào yòng |
| law of diminishing marginal utility/lɔː ɒv dɪˈmɪnɪʃɪŋ ˈmɑːdʒɪnl juːˈtɪlɪti/ | 边际效用递减规律 | biān jì xiào yòng dì jiǎn guī lǜ |
Why the fifth slice isn't worth it
- The first slice of pizza is amazing. The second, great. By the fifth... meh.
- Each extra slice gives less added enjoyment than the one before.
- Smart choices are rarely "all or nothing" — they happen one unit at a time.
- Economists call this thinking at the margin 边际.
为什么第五块不值得
- 第一块披萨美味极了。第二块,很棒。到第五块……也就那样。
- 每多一块带来的额外享受,都比前一块更少。
- 聪明的选择很少是"要么全要、要么不要"——它们一次只多决定一个单位。
- 经济学家把这种思考叫做在边际上(margin)权衡。
Think at the margin
- Marginal benefit 边际收益 (MB) is the extra benefit from one more unit.
- Marginal cost 边际成本 (MC) is the extra cost of one more unit.
- The rule for any rational choice: keep going while $MB > MC$, and stop where $MB = MC$.
- That point gives the greatest total net benefit — go further and each extra unit costs more than it is worth.
在边际上思考
- 边际收益(marginal benefit,MB)是多一个单位带来的额外收益。
- 边际成本(marginal cost,MC)是多一个单位带来的额外成本。
- 任何理性选择的规则:只要 $MB > MC$ 就继续,直到 $MB = MC$ 处停下。
- 那一点带来最大的总净收益——再往前,每多一单位的成本都超过它的价值。
A rational decision-maker keeps doing an activity as long as: · 一个理性的决策者会一直做某项活动,只要:
Keep going while MB > MC; stop where MB = MC for the greatest net benefit. · 只要 MB > MC 就继续;在 MB = MC 处停下,净收益最大。
The 4th cookie has a marginal benefit of 6 dollars and a marginal cost of 2 dollars. By how much (in dollars) does making it change your net benefit? · 第 4 块饼干的边际收益是 6 美元,边际成本是 2 美元。做出它会让你的净收益改变多少美元?
Net benefit rises by $MB - MC = 6 - 2 = 4$. Since MB > MC, it is worth making. · 净收益增加 $MB - MC = 6 - 2 = 4$。因为 MB > MC,值得做。
Select all · 所有 true statements about the best quantity $Q^*$ where $MB = MC$. · 选出关于 $MB = MC$ 处最佳数量 $Q^*$ 的所有正确说法。
At $Q^*$, MB = MC gives the maximum net benefit; MB is highest at the first · 第一个 unit, not at $Q^*$. · 在 $Q^*$,MB = MC 带来最大净收益;MB 在第一个单位处最高,而不是在 $Q^*$。
Diminishing marginal utility
- Utility 效用 is the satisfaction a good gives you.
- The law of diminishing marginal utility 边际效用递减规律 says each extra unit adds less satisfaction than the last.
- The first slice of pizza has high marginal utility; the fifth adds little.
- This is exactly why demand curves slope downward — you only buy more if the price falls to match the smaller benefit.
边际效用递减
- 效用(utility)是一种商品带给你的满足感。
- 边际效用递减规律(law of diminishing marginal utility):每多一个单位增加的满足感,都比上一个更少。
- 第一块披萨的边际效用很高;第五块几乎没加多少。
- 这正是需求曲线向下倾斜的原因——只有价格降下来、配得上更小的收益,你才会买更多。
Watch marginal utility fall · 看边际效用如何下降
Each extra unit adds less satisfaction than the last — a falling curve. That is the law of diminishing marginal utility, and it is why demand slopes down. · 每多一个单位增加的满足都比上一个少——一条下降的曲线。这就是边际效用递减规律,也是需求向下倾斜的原因。
The law of diminishing marginal utility says that as you consume more of a good: · 边际效用递减规律说,当你消费某商品越来越多时:
Marginal (extra) utility falls with each unit — total utility still rises, just more slowly. · 边际(额外)效用随每个单位递减——总效用仍在上升,只是变慢了。
Diminishing marginal utility helps explain why demand curves slope downward. · 边际效用递减有助于解释需求曲线为什么向下倾斜。
Because extra units are worth less, you only buy more when the price falls. · 因为多出的单位价值更低,只有价格下降时你才会买更多。
Spend a budget for the most satisfaction
- To get the most from a fixed budget, compare the marginal utility per dollar across goods.
- The utility-maximizing rule: set $\dfrac{MU_x}{P_x} = \dfrac{MU_y}{P_y}$.
- If one good gives more utility per dollar, shift spending toward it — until the ratios balance.
- That balance is the most satisfaction your money can buy.
用预算买到最多的满足
- 要让固定预算发挥最大作用,就比较各种商品的每元边际效用。
- 效用最大化法则:让 $\dfrac{MU_x}{P_x} = \dfrac{MU_y}{P_y}$。
- 如果某种商品每元带来的效用更高,就把支出向它倾斜——直到各比值相等。
- 这种平衡,就是你的钱能买到的最多满足。
To maximize utility from a budget, marginal utility per ______ should be equal across all goods. · 要让预算的效用最大化,每______的边际效用应在所有商品间相等。
The utility-maximizing rule equalises $MU/P$ across goods — marginal utility per dollar. · 效用最大化法则让各商品的 $MU/P$ 相等——即每元的边际效用。
Think at the margin: do one more unit while MB > MC, and stop at MB = MC. Extra units give less satisfaction (diminishing marginal utility), which is why demand slopes down. Spend a budget so marginal utility per dollar is equal across all goods.
在边际上思考:只要 MB > MC 就多做一个单位,到 MB = MC 停下。多出的单位带来更少的满足(边际效用递减),这就是需求向下倾斜的原因。分配预算时,让每元边际效用在所有商品间相等。