reject the separability between meat and fish products. The empirical model specified for this
study, therefore, includes both meat and fish products.
Almost Ideal Demand System (AIDS) and Rotterdam Model
Two different demand systems (AIDS and Rotterdam model) are considered to estimate
meat and fish product demand in Korea. Assuming that meat and fish products are not separable,
the Rotterdam model developed by Theil and Barten is specified for the Korean meat and fish
industry as follows:
n
(1) wξ.∆ logqi = ∑ Yijδ logPj + βiDQ, i = 1,2,...,n,
j=1
where i and j are indexes for goods, qi is the quantity demanded of the ith good, and pj is the
price of jth good within the group. wi is the average of wi t and wi t-1, budget shares of ith good
on time t and t-1. ∆ denotes the first-difference operator ( ∆ logqi=logqi,t-logqi,t-1 ). DQ
represents the real income term.
The theoretical restrictions of adding-up, homogeneity, and symmetry are satisfied by the
following parametric restrictions on the Rotterdam model.
nn
(2) Adding-up: ∑γij = 0, ∑βi = 1.
i=1 i=1
n
Homogeneity: ∑γij = 0.
j=1
Symmetry: γij = γji .