Weak Separability Testing And Estimation Of Selected Food Commodities Demand System In Urban Households Of Iran (Case Study of: Citrus Fruits, Cucurbits and Vegetables)

The separability of consumer desires is a necessary and sufficient condition for multi-stage budgeting and Collectivization is consistent of commodity where costs are allocated between edible groups using price indices and intergroup allocations are made independently of other groups. Given the high share of Citrus fruits, Cucurbits and vegetables types (29/5% percent of household food and beverage expenditure) in the household budget and the important nutritional role of fruits in people's health, in this study, to determine the consumption pattern of selected products in Iran used to Rotterdam demand function. In empirical studies of demand, the concept of separation is used to correctly estimate demand function and limit the number of parameters. For this purpose, data related to price index and cost of selected commodities (Citrus fruits, Cucurbits, vegetables) central bank over the years 2016 in urban households of iran were used. The results of the separability tests support the hypothesis that consumers first divide their income between selected commodities in three groups (Citrus fruits, Cucurbits, vegetables) assigns and then approves the income allocation action between the types of its subgroups that are grouped. Also results of system estimation showed that all groups had a negative intrinsic price elasticity. In the meantime, the price elasticity of groups Citrus fruits ( orange , Tangerines, Lemon) , Cucurbits fruits ( potato, tomato, onion) and vegetables ( Leafy) are respectively equal to -0.83, -0.48 and -0.91.