平狄克中级微观经济学课件厦门大学王瑞芳micro4章节幻灯片.ppt

* 73 * 77 * 84 * 84 * 92 * 96 * 97 * 106 * 111 * 117 * 121 * 124 * 64 * 66 * 75 * 75 * 75 * 33 * 38 * 39 * 41 * 42 * 52 * 55 * 72 * 77 * 85 * 96 * 102 * 111 * 123 * 132 * 16 * 17 * 18 * 19 * 20 * 21 * 22 * 27 * 36 * 39 * 46 * 54 * q0 Lost profit for qq q* Lost profit for q2 q* q1 q2 A Competitive Firm Making a Positive Profit 10 20 30 40 Price ($ per unit) 0 1 2 3 4 5 6 7 8 9 10 11 50 60 MC AVC ATC AR=MR=P Output q* At q*: MR = MC and P ATC D A B C q1 : MR MC and q2: MC MR and q0: MC = MR but MC falling * Would this producer continue to produce with a loss? A Competitive Firm Incurring Losses Price ($ per unit) Output AVC ATC MC q* P = MR B F C A E D At q*: MR = MC and P ATC Losses =(P- AC) x q* or ABCD * 选择短期产量 经理的一些成本考虑： 平均可变成本不应用以替代边际成本。 厂商的会计分类账的单独科目可能有两个组成部分，但只有一个部分涉及到边际成本。 在确定边际成本时应计入机会成本。 * 竞争性厂商的短期供给曲线 厂商供给曲线是位于平均可变成本最低点以上的边际成本曲线。PP67 因报酬递减，因此供给曲线是向上倾斜的。 投入品价格变化，厂商将改变产出水平使其边际成本等于改变后的价格。 PP68。 * A Competitive Firm’sShort-Run Supply Curve Price ($ per unit) Output MC AVC ATC P = AVC What happens if P AVC? P2 q2 P1 q1 The firm chooses the output level where MR = MC, as long as the firm is able to cover its variable cost of production. * MC2 q2 Input cost increases and MC shifts to MC2 and q falls to q2. MC1 q1 The Response of a Firm toa Change in Input Price Price ($ per unit) Output $5 Savings to the firm from reducing output * 市场（短期）供给弹性 供给完全无弹性： 厂商的厂房设备被充分利用，因此要提高产量必须建新厂房，而这需要较长一段时间，因此短期内供给无法提高。 供给完全弹性： 边际成本恒定。 * 短期厂商剩余 所有产品的市场价格和边际成本之差相加。 图PP71 厂商剩余与利润密切相关，但并不相等： 短期尺度下当固定成本为正时，厂商剩余大于利润。PS?， * A D B C Producer Surplus Alternatively, VC is the sum of MC or ODCq* . R is P x q* or OABq*. Producer surplus = R - VC or ABCD. Producer Surplus for a Firm Price ($ per unit of output) Output AVC MC 0 P q* At q* MC = MR. Between 0 and q , MR MC for all units. * D P* Q* Producer Surplus Market producer surplus is the difference between P* and S from 0 to Q*. Producer Surplus for a Market Price ($ per unit of output) Output S * 选择长期产量