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Pierre André Chiappori (Columbia) "Family Economics" - Cemmap

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generating the aggregate demand:<br />

5. Empirical issues for the collective model 215<br />

piqi = pici+ £ α a ¡ ¢ ¡ ¡ ¢¢¤ 0 x z b 0 x z<br />

i μ + μ x + μ z + αi 1 − μ + μ x + μ z Y (5.20)<br />

and for public goods:<br />

PjQj = PjCj + £ α a ¡ ¢ ¡ ¡ ¢¢¤ 0 x z b 0 x z<br />

j μ + μ x + μ z + αj 1 − μ + μ x + μ z Y<br />

Here, ci = ca i + cb ³<br />

i and Y = x − P<br />

i,s pics P<br />

i − j PjCj<br />

´<br />

. The household<br />

demand is thus a direct generalization of the standard LES, with additional<br />

quadratic terms in x2 and cross terms in xpi and xPj, plus terms involving<br />

the distribution factor z; one can readily check that it does not satisfy<br />

Slutsky symmetry in general, although it does satisfy SNR1.<br />

A first remark is that ca i and cbi cannot be individually identified from<br />

group demand, since the latter only involves their sum ci. As discussed<br />

above, this indeterminacy is however welfare irrelevant, because the collective<br />

indirect utilities of the wife and the husband are, up to an additive<br />

constant:<br />

W a (p, P, x, z) = logY +log ¡ μ 0 + μ x x + μ z z ¢ − X<br />

α a i log pi − X<br />

i<br />

j<br />

α a j log Pj<br />

W b (p, P, x, z) = logY +log ¡ 1 − ¡ μ 0 + μ x x + μ z z ¢¢ − X<br />

α b i log pi − X<br />

which does not depend on the cs i . Secondly, the form of aggregate demands<br />

is such that private and public goods have exactly the same structure. We<br />

therefore simplify our notations by defining<br />

ξi = qi for i ≤ n, ξi = Qi for n

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