Wi
Wi
Wi
Σn , n Л11 c ⅛P∙") - 'π a (p)ʌ п π ,
J=1 7ij 1ПPj + βi к ln Ъ (р) - ln a (р) )β0 П P
N
ai + ∑ 7ij lnPj + Pi (ln М - ln a (p))
j=l
N
ai + Σ 7ij ln Pj + Pi ln
j=l
(34)
where P is a price aggregator
N ɪ NN
ln P = <>0 + Vv ln Pi +2∑ ∑7 ij ln Pi ln Pj (35)
i=l i i=l j=l
and where
7ij = ɪ (Pij + 7ji) ∙
(36)
The parameter restrictions (28) - (30) of the cost function (27) should in
general also hold for the budget share equation (34). Only the restrictions
(29) and (30) have to be changed slightly due to equation (36) to:
N
∑ 7ij = 0 ∀j,
(37)
i=l
and
7 ij = 7ji∙ (38)
As [11]Deaton and Muellbauer (1980) show, adding-up (ɪ) Wi = ɪ) re-
quires the parameter restrictions (28) und (37) to be satisfied, the restriction
(37) ensures the homogeneity of degree 0 in p und M of the budget share
equation (34) and restriction (38) is the requirement for a symmetric Slutsky
matrix. The AIDS can either be estimated by directly imposing the re-
strictions (28) - (30) or by testing the restrictions after having estimated the
model without restricitions. Taking the parameter restricitons (28), (37) and
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