Investigating the Changes in consumer preferences for solid and liquid edible oils (Application of nonparametric test, case study: Fars province)

In analysing consumer rational behaviour, the proof of a neoclassical utility function for consumption data is inevitable. Researches of demand functions will be correct when the demand function and the basis of utility are a good approximation of the utility function and the actual demand. In this study, the revealed preferences method was used to test the stability and structural failure in Fars province's consumer preferences for the oil from 1990 to 2016. Based on the results, only three violations were found in the total data in the years 2002 & 1993, 2003 & 1997, 2004 & 1997. The Kruskal-Wallis test showed that these inconsistencies weren't due to change in preferences and may be unstable due to errors in measurements or nonlinear momenta, and the assumption of rational behaviour was confirmed. Thus, the consumption data of the oil basket Fars province's households can be interpreted using a neoclassical utility function.