A globally flexible,quadratic almost ideal demand system: an application to demand for meats and fish in Taiwan

A new demand system, called a globally flexible, quadratic almost ideal demand system (GF–QUAIDS), integrates both the quadratic Engel curve and the Fourier series. This novel GF–QUAIDS model is applied to study the demand for meats and fish in Taiwan. Empirical results show that the GF–QUAIDS fits the data well and that, by using the likelihood ratio test, its nested models are rejected, including the locally flexible functional form and the linear Engel curve. Nevertheless, other empirical model-selection measures indicate that the GF–QUAIDS can be as good as its famous nested models such as the AIDS, QUAIDS and GF–AIDS.