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Chapter 9 Buying And Selling People earn their income buy selling things that they own. Endowment: (w 1 ,w 2 ) Gross demand: (x 1 ,x 2 ) Net demand: (x 1 -w 1 ,x 2 -w 2 ) (observed) x 1 -w 1 >0, net buyer, net demander x 1 -w 1 <0, net seller, net supplier
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Chapter 9 Buying And Selling • People earn their income buy selling things that they own. • Endowment: (w1,w2) • Gross demand: (x1,x2) • Net demand: (x1-w1,x2-w2) (observed) • x1-w1>0, net buyer, net demander • x1-w1<0, net seller, net supplier • Budget constraint becomes: p1x1+ p2x2 = p1w1+ p2w2
Changing the endowment from (w1,w2) to (w1’,w2’) so that p1w1+ p2w2 < p1w1’+ p2w2’, then the consumer must be better off (the point is no need to consume endowment and the budget set is larger). • Suppose p1 decreases, (w1,w2) always on the budget line: before change, a net seller of good 1, now could be a net seller (worse off) or a net buyer (?); before, a net buyer, now must a net buyer (better off)
Revisit Slutsky equation • p1w1+ p2w2, no way to hold nominal income fixed when, say, p1 changes • Holding purchasing power fixed (SE) • Holding nominal income fixed (OIE) (ordinary income effect) • In addition, when prices change, the value of the endowment bundle changes, this additional income effect is called the endowment income effect (EIE)
Abbreviate p1w1+ p2w2 by pw. • x1(p1, pw) → x1(p1’, p1’x1(p1, pw)+p2x2(p1, pw)) (SE) → x1(p1’, pw) (OIE) → x1(p1’, p1’w1+ p2w2) (EIE) • A dairy farmer produces 40 quarts of milk per week, p1=3 and p1’=2, x1=10+m/(10p1) • [10+2*40/(10*2)]-[10+3*40/(10*2)]=-2 (EIE)
p1→ p1’ • m → m’ → m’’ • m = p1x1+ p2x2 = p1w1+ p2w2 • m’ = p1’x1+ p2x2 • m’’= p1’w1+ p2w2 • m’’-m=(p1’-p1)w1 and m’-m=(p1’-p1)x1
x1(p1’,m’’)-x1(p1,m)=[x1(p1’,m’)-x1(p1, m)]+[(x1(p1’,m)-x1 (p1’,m’)]+[x1(p1’,m’’)-x1(p1’,m)] (Slutsky identity) • TE/(p1’-p1)=(x1(p1’,m’’)-x1(p1,m)) /(p1’-p1) • SE/(p1’-p1)=(x1(p1’,m’)-x1(p1,m)) /(p1’-p1) • OIE/(p1’-p1)=(x1(p1’,m)-x1(p1’,m’)) /(p1’-p1) =-[(x1(p1’,m’)-x1(p1’,m)) /(m’-m)] x1(p1, m)) • EIE/(p1’-p1)=(x1(p1’,m’’)-x1(p1’,m))/(p1’-p1)=[(x1(p1’,m’’)-x1(p1’,m))/(m’’-m)] w1
∆xa/∆pa = ∆xas/∆pa+(wa-xa) ∆xam/∆m • Apply to labor supply • M: non labor income • w: wage rate • p: price of consumption • C: consumption, R: leisure, R’: max • pC=w(R’-R)+M, pC+wR=wR’+M (full income or implicit income, the value of her endowment of consumption and her endowment of time)
Consider an increase in w, what will happen to R? • ∆R/∆w = ∆Rs/∆w+(R’-R) ∆Rm/∆m • SE is (-) and assuming leisure is normal, then total IE is (+), since L=R’-R, this means we might have a backward bending labor supply if the IE is large enough • Note that if (R’-R) is large (work hard enough) then IE is likely to be big
Overtime and labor supply (increase w, may reduce labor because of IE, but overtime wage w’>w is a pure SE)