El Niño southern oscillation and its effects on world vegetable oil prices: assessing asymmetries using smooth transition models

In this research, we examine the effects of El Niño southern oscillation (ENSO) on market dynamics of major vegetable oil prices. We adopt a smooth transition vector error correction modelling framework to analyse the impacts of ENSO events on the vegetable oil prices and, more interestingly, to investigate the asymmetric nature of the ENSO dynamics and price responses to ENSO shocks. The results confirm self‐exciting type nonlinearities in the ENSO dynamics, and presence of the so‐called transactions cost band in the system of vegetable oil prices. These nonlinearities yield the history‐specific asymmetries in the vegetable oil price dynamics, wherein effects of ENSO shocks on the ENSO dynamics and the vegetable oil prices vary considerably between different ENSO regimes. In general, positive deviations, El Niño events, result in the vegetable oil price increase, while negative deviations, La Niña events, result in decrease in the prices. We illustrate these effects using generalised impulse‐response functions and the derived asymmetry measures.