Presentation is loading. Please wait.

Presentation is loading. Please wait.

Internet Economics Basics of Supply Side

Similar presentations


Presentation on theme: "Internet Economics Basics of Supply Side"— Presentation transcript:

1 Internet Economics Basics of Supply Side
Shi-Chung Chang Yi-Nung Yang

2 Outline Law of supply Factors affecting supply Elasticity of supply
Profit Maximization Production function Cost function Cost curves Market Supply A First look at the Internet Industry

3 Law of Supply Definition: A simple supply function
Quantity demanded is positively related to price, cetris paribus. i.e., Qs ↑(↑) <=> P↓(↓) A simple supply function Qs = D(P, W), W: other factors affecting supply  Qd / P>0, implied by the law of supply. e. g., W =>技術、生產要素價格、其他商品價格...

4 Factors Affecting Supply
以撥接 ISP 經營為例: Qsc: 可供上網連線時間(min), Pc: 連線價格 ($/min) Own price: Pc↑ => Qsc↑ 技術: A↑ => Qsc↑, 生產要素價格: Router價格, 專線、市內電話線路費 其他產品價格: Cable連線價格 預期未來連線價格: ISP 廠商數目 供給線移動 價格不變下, 供給↑(↓) 供給線右(左)移

5 Elasticity of Supply 供給彈性
衡量價格變動對供給量變動的影響 供給彈性= (供給量變動的百分比/價格變動百分比) >1 => elastic 富有彈性, <1 => inelastic缺乏彈性

6 Elasticity of Supply (2)
供給彈性之簡單應用 假設你經營一家ISP,若某產業分析報告指出,,台灣ISP產業之供給彈性為 1.2, 且台灣明年撥接需求量將成長240%, 在其他狀況不變下, 則可預期貴公司之營收可成長? 價格增加100%, 所以營收增加100% 分析重點 產業供給線 個別廠商供給線

7 Profit Maximization Profit maximization is economic approach to a firm’s behavor Profit = Total Revenue - Total Cost = PQ - TC

8 Production Function Key assumptions Production function: Q = f(L, K)
more inputs generate a larger output marginal product is diminishing e.g., 電腦機房人員 Production function: Q = f(L, K) Total Product (TP, 總產量) Marginal Product (MP, 邊際產量) MPi= f/  i>0, i = L (勞動力), K (資本財) MPi/  Q<0 Average Product (AP, 平均產量) APi = Q/i , i = L, K 例: Q=f(L, K) = A La Kb

9 TP, MP, and AP 之關係 TP is increasing in L, if Q<L3 MP curve:
a’ 點之MP最大 AP curve: b’ 點AP最大 Question: MP線通過AP線最高點?

10 Cost function TC (total cost) = TVC + TFC = 總變動成本+總固定成本
變動成本: 隨產量增加而增加之成本 固定成本: 不隨產量增加而增加之成本 平均成本 ATC (AC) = AVC + AFC 邊際成本 Marginal Cost (MC) =  TCi/  Q 增加1單位產量所需增加之成本 MC =  TCi/  Q =  TVCi/  Q (why??) 典型之成本範例: TC = wL + rK w: 工資, r: 利率

11 Cost Curves MC vs MP curves AVC vs AP curves
MP curve 為向下凹, 則MC curve為向上凹 e.g., 假設只有一種變動成本之生產投入: 勞動L AVC vs AP curves AP curve 為向下凹, 則AVC curve為向上凹

12 Cost curves

13 AFC, AVC, ATC, and MC AC = AVC+AFC MC 通過AC和AVC之最低點

14 MC 通過AC和AVC之最低點 AC之最低點斜率 = 0 類似方法可證 MC通過AVC之最低點

15 Long-run v.s. Short-run Cost
長期: 所有生產要素投入量皆可變動之期間 長期下, 所有生產成本皆為變動成本 LAC: 長期平均成本 短期: 只要有一種生產要素投入量不可變動之期間 短期下, 有任一種固定成本存在 SAC: 短期平均成本

16 LAC v.s. SAC

17 Economies of Scale 經濟規模
IRS: Increasing returns to scale 規模報酬遞增 規模經濟, i.e., Q↑ AC↓ CRS: Constant returns to scale 固定規模報酬 規模報酬不變, i.e., Q↑ AC不變 DRS: Decreasing returns to scale 規模報酬遞減 規模不經濟, i.e., Q↑ AC↑

18 Economies of Scale

19 Profit Maximization 利潤 = 總收入 - 總成本 TR and MR Max  (= TR - TC) 個別廠商
總收入: TR = PQi 邊際收入: MR =  TR /  Qi Max  (= TR - TC) FOC:   /  Qi = ( TR /  Qi) - ( TC /  Qi) =0 = MR -MC =0 廠商利潤極大之生產量Q*i必使 MR = MC 個別廠商 當個別廠商產量不足以影響市場價格時  P /  Qi =0 MR= TR /  Qi =  (PQi) /  Qi = P

20 Total Revenue and Cost curves
Profit TR TC

21 個別廠商長期、短期經營決策  >0:價格>P2  =0:價格=P2  <0: 價格<P2
有「超額利潤」 繼續經營  =0:價格=P2 仍有「正常利潤」 可以繼續經營  <0: 價格<P2 長期: 停止營業 短期: PP3:暫時繼續經營 P< P3 : 關門大吉

22 Short-run Supply Curve
廠商短期供給線 MC 曲線大於AVC最低點的部分 S = MC > AVCmin

23 Market Supply 市場供給: 同一價格下, 所有個別廠商供給量之總和 Qs = Qs1+ Qs2+ Qs3+ Qs4+... S2
市場供給: 同一價格下, 所有個別廠商供給量之總和 Qs = Qs1+ Qs2+ Qs3+ Qs4+... S2 S1 P QC Firm 1 S2 + P QC Firm 2 = P QC Market Supply S S1

24 A first look at the Internet Industry
Fixed Cost is high MC  0 P=MC D1 & S1 Q1: 賠錢 D2 & S1 訂價=P1 網路塞車 擁塞成本 D2 & S2 Q2: QM: 現有技術最大產能


Download ppt "Internet Economics Basics of Supply Side"

Similar presentations


Ads by Google