第 13 章不確実性と情報（ 4 章 3 節を含む）

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第 13 章不確実性と情報（ 4 章 3 節を含む）. パレート最適が達成するための条件：市場の普遍性：すべての財に対して市場が存在し，交換が行われる。完全競争の条件：すべての市場で完全競争が支配し，すべての生産要素が企業間・産業間で自由に移動できる。凸環境の条件：効用関数・生産関数は他の経済主体の消費量・産出量から独立であり，されに限界代替率逓減の法則，限界費用逓減の法則が成り立つ。安定性の条件：競争均衡が安定的で，均衡はずれても素早く均衡が回復される。 - PowerPoint PPT Presentation

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*13 43market failure
*13 2riskuncertainty
*13 riskuncertainty
*13 law of large numbers
*13 law of large numbers PC
*13 law of large numbers
*13 13.1 1000100012 3456

248 163264
*13 13.1 1000100012 3456

248 1632641/2 1/4 1/8 1/16 1/32 1/64 1/221/441/881/16161/3232111
*13 13.2 Ux1/2 Ux100 4001/2 100U11001/210 400U24001/220 1001/24001/2 250 u101/2201/215250 U2501/25101/215.81250250
*13 13.2 U1/10x2 Ux40 101/2 40U11/10402160 10U2 1/10102 10 401/2101/2 25 u1601/2101/28525 U1/1025262.50 2525
*13 13.2 Ux2 Ux10 401/2 10U110212 40U240242 101/2401/2 25 u121/2421/22725 U2522702525
*13 13.2 2
*13 13.2 22500100%70050% 30050%50040300.5460.538
*13 13.2 22500100%70050% 30050%50040300.5460.53838
*13 13.2 4001/410003/4850 1001/41403/4 130150600416001/4150
*13 13.2 4001/410003/4850 1001/41403/4 130150850137850
*13 13.2 4001/410003/4850 1001/41403/4 1301501307007007850700150 risk premium
*13 13.2 850 risk premium0850 risk premium0
*13 13.3 UU(x) 1/2x1 1/2x2 u(x1, x2)1/2U(x1)1/2U(x2) x1=x2=x u(x, x) 1/2U(x)1/2U(x)U(x) Ux1/2 1/2100 1/24001/2100 1/2400250 u(100, 400)1/21001/2 1/24001/215225 u(225, 225)U(225)2251/215
*13 13.3 UU(x) 1/2x1 1/2x2 u(x1, x2)1/2U(x1)1/2U(x2) x1=x2=x u(x, x) 1/2U(x)1/2U(x)U(x) Ux1/2 1/2100 1/24001/2100 1/2400250 u(100, 400)1/2101/2 1/2201/215225 u(225, 225)U(225)2251/215225900225 u(0, 900)1/201/2 1/29001/215 u(900, 0)1/29001/2 1/201/215900
*13 13.3 UU(x) 1/2x1 1/2x2 u(x1, x2)1/2U(x1)1/2U(x2) x1=x2=x u(x, x) 1/2U(x)1/2U(x)U(x)
*13 13.3 225 50% 400%225900300 b 1w1225b 1w2(225b)4b2253bb225w1b(w2225)/3 225w1(w2225)/3 w29003w1w29003w1b225b3b2253b

w1 w202252252250900b225b2253b7575675
*13 13.3 225 50% 400%225900300 b 1w1225b 1w2(225b)4b2253b b15067575b150

w1 w202252252250900b225b2253b15075675
*13 13.3 225 50% 400%225900300 b 1w1225b 1w2(225b)4b2253b b225b225

w1 w202252252250900b225b2253b15075675
*13 13.3 225 50% 400%225900300b225 b225 0900 b150 75675
*13 13.4
*13 13.4

or (moral hazard)
*13 13.4

X
*13 13.4 monitoring
*13 13.4 2 principalagent
*13 13.4

UUEWU/E < 0 U/W > 0WEdW/dE > 0U/E(U/W)(dW/dE) WE2
*13 13.4

WE2
*13 13.4 adverse selection Akerloflemon
*13 13.4 adverse selection q 0q111/2 q(3/2)q(3/2)qqqqqq1q(3/2)qq> (3/2)qqSD
*13 13.4 adverse selection q 0q111/2 q(3/2)q(3/2)qqqqqq1(3/2)qqq*(3/2)q*< (3/2)q*qDqS(3/2)q*
*13 13.4 adverse selection q 0q111/2 q(3/2)q(3/2)qqqqqq q*1/2(3/2)q* S
*13 13.4 adverse selection lemon
*13 13.4 adverse selection
*13 13.4 adverse selection or 2xc c2(x) > c1(x)

MC2(x) > MC1(x)a 1 MC1(x1) MC2(x2)1x2*x1*

MC2MC11x1*x2*
*13 13.4 adverse selection or 2xc c2(x) > c1(x) MC2(x) > MC1(x)b x2*S2C2(x2*)x1*S1C1(x1*) x2*x1* S1C1(x1*)0x2* S2C1(x2*) > 0

MC2MC11x1*x2* C1(x1*)
*13 13.4 adverse selection or 2xc c2(x) > c1(x) MC2(x) > MC1(x)b x2*S2 x1*S1 S2C1(x2*) MC2MC11x1*x2*S2S1 C1(x1*)
*13 13.4 adverse selection or 2xc c2(x) > c1(x) MC2(x) > MC1(x)b x2S'2 x1*S1 S2C1(x2) x2 < x2 * MC2MC11x1*x2*S'2S1 C1(x1*)x2
13 13.4 adverse selection

*
13 13.4 adverse selection or

*
13 13.4 adverse selection *
13 13.4

*