US import demand for apple: source differentiated almost ideal demand system approach

We adopted a restricted version of Source Differentiated Almost Ideal Demand System (RSDAIDS) to analyse the US import demand for fresh apples, apple juice and other processed apples after differentiating each type of apple by import origins. Seasonality and time trend variables were included in the RSDAIDS model and the general demand restrictions of adding-up, homogeneity and slutsky symmetry were imposed. The system of equations is then estimated using Seemingly Unrelated Regression (SUR) and the results of the estimation are presented in the form of parameter estimates, as well as price and expenditure elasticities.