消費者余剰と生産者余剰
導入済み| English | 意味 |
|---|---|
| consumer surplus/kənˈsuːmə ˈsɜːpləs/ | 消費者余剰 |
| producer surplus/prəˈdjuːsə ˈsɜːpləs/ | 生産者余剰 |
A decision you can investigate
- A buyer would pay more than the market price; a seller would accept less.
- The transaction creates gains on both sides, even though only one market price is paid.
Build the explanation
- Consumer surplus 消费者剩余 is willingness to pay minus actual payment, summed across purchased units. Producer surplus 生产者剩余 is receipts above the minimum required to supply those units. On linear diagrams they can be triangle areas, but not every curve produces a triangle.
- These are gains from trade under the model. Producer surplus is not automatically accounting profit because fixed costs and the time period matter. Consumer surplus is not a cash refund.
Work through the evidence
- Use Qd=120−2P and Qs=2P. Inverse demand intercepts price 60; inverse supply begins at 0. Equilibrium is P=30,Q=60. CS=½ × (60−30) × 60=900; PS=½ × (30−0) × 60=900 currency units.
- Demand shifts to Qd=160−2P, with intercept 80. New equilibrium P=40,Q=80 gives CS=½ × (80−40) × 80=1600 and PS=½ × 40 × 80=1600. Consumers pay a higher price yet surplus rises in this particular case because willingness to pay and quantity changed too.
元の消費者余剰はどれですか？
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
三角形の面積は ½ × 30 × 60 です。
指定された需要シフト後の消費者余剰はどれですか？
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
新しい高さは 80−40=40 で、底辺は 80 です；その積を半分にしてください。
消費者余剰とは、売主が買い手に返す金額のことである。
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
これは還付金を計測するものではなく、支払い超過の評価額を表す。
Test the limits
- A higher price alone, with the original demand curve unchanged, usually reduces consumer surplus. The shift case has a different demand schedule, so a price-only comparison is incomplete.
- Adding CS and PS is not a complete social-welfare measure when third-party effects or distributional values matter. Demand represents willingness and ability to pay; limited incomes can affect the measured valuation.
なぜ生産者余剰は常に利益ではないのか？
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
測定方法が同一期間で同一コストを控除する必要はない。
Apply and explain your answer
- Why does the higher price after the demand shift not by itself prove lower consumer surplus?
- The demand curve and purchased quantity also changed, so the whole surplus area must be recalculated.
用語とそれぞれの意味を結びつけよ。
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
各用語を、その明示された経済的関係に用いること。
Use the terms precisely
- consumer surplus: Total willingness to pay above the payment for units purchased.
- producer surplus: Receipts above the minimum required to supply the units sold.
Use Qd=120−2P and Qs=2P. Inverse demand intercepts price 60; inverse supply begins at 0. Equilibrium is P=30,Q=60. CS=½ × (60−30) × 60=900; PS=½ × (30−0) × 60=900 currency units. Demand shifts to Qd=160−2P, with intercept 80. New equilibrium P=40,Q=80 gives CS=½ × (80−40) × 80=1600 and PS=½ × 40 × 80=1600. Consumers pay a higher price yet surplus rises in this particular case because willingness to pay and quantity changed too.
A higher price alone, with the original demand curve unchanged, usually reduces consumer surplus. The shift case has a different demand schedule, so a price-only comparison is incomplete. Adding CS and PS is not a complete social-welfare measure when third-party effects or distributional values matter. Demand represents willingness and ability to pay; limited incomes can affect the measured valuation.
Consumer surplus is willingness to pay minus actual payment, summed across purchased units. Producer surplus is receipts above the minimum required to supply those units. On linear diagrams they can be triangle areas, but not every curve produces a triangle.