“…2 Specifically, we modify the GEASI model by incorporating a time transition function in the spirit of Ohtani and Katayama (1986) to examine potential structural preference shifts. While retaining all of the desirable properties of the previous workhorse demand models such as the Almost Ideal Demand System (AIDS) (Deaton and Muellbauer, 1980;Hovhannisyan and Khachatryan, 2017), the GEASI system offers a number of unique advantages due to its ability to: (i) account for unobserved consumer heterogeneity, (ii) allow for unrestricted Engel curves whose structure is determined by data rather than being imposed a priori (Pendakur, 2009;Samuelson, 1948;Stone, 1954), (iii) account for potential pre-commitment bias in empirical settings, where pre-committed quantities constitute an integral part of consumer demand (Hovhannisyan and Shanoyan, 2019;Rowland, Mjelde, and S. Dharmasena, 2017), and (iv) assure invariance of elasticity estimates to the data measurement units (Alston, Chalfant, and Piggott, 2001).…”