Türkiye’de Gıda Fiyatlarının Fourier Alanda Belirleyicileri

This study investigates the determinants of food prices in the Turkish economy during the period from January 2006 to January 2025, a time frame marked by the implementation of an explicit inflation targeting strategy. Utilizing Fourier time series methods, the empirical analysis employs key macroeconomic variables including the inflation rate derived from the food and non-alcoholic beverages price index, the industrial production index, the nominal exchange rate of the US dollar, and the global price of Brent crude oil. All variables in the model possess a Fourier unit root at their level values, with a frequency degree of one. The model also reveals the existence of a Fourier cointegration relationship. Accordingly, a 1% increase in industrial production and the nominal exchange rate leads to an average rise in food prices by 0.42% and 0.98%, respectively. The parameter associated with crude oil prices, however, is found to be statistically insignificant. The sine function is statistically significant at the 1% level, suggesting vertical movements in cyclical fluctuations, while the cosine function, though statistically insignificant, indicates no horizontal shift or phase displacement within the business cycle. According to the results of the Fourier causality tests, there exists bidirectional, yet solely linear causality between food prices and industrial production. Moreover, there is strong bidirectional Fourier causality between food prices and the nominal exchange rate. Although a weak causality is observed from food prices to crude oil prices, a strong Fourier-based causality from oil prices to food prices indicates the operative role of cost-push inflation mechanisms.