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The Almost Ideal Demand System (AIDS) (1980) is a consumer demand model used primarily by economists to study consumer behavior. The AIDS model gives an arbitrary first-order approximation to any demand system and has many desirable qualities of demand systems. For instance it satisfies the axioms of order, aggregates over consumers without invoking parallel linear Engel curves, is consistent with budget constraints, and is simple to estimate. ==Model== The AIDS model is based on a first specification of a cost/expenditure function c(u,p): : with x total expenditures, , and P is a price index: : . Under relevant constraints on the parameters , These budget shares equations share the properties of a demand function: * homogoeneous of degree 0 in prices and total expenditure * sum of budget shares add up to 1 (i.e., ) * satisfy the symmetry of the Slutsky matrix 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「almost ideal demand system」の詳細全文を読む スポンサード リンク
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