US Trade Policy Uncertainty and Nigeria’s Participation in Global Value Chains: Evidence from Frequency Domain Causality, Wavelet Coherence Analysis, and Time-Varying Causality

Abstract

This study examines for the first time whether trade policy uncertainty emanating from the United States significantly predicts Nigeria’s participation in global value chains. It further examines the kind of global value chain participation in Nigeria (forward or backward linkages) that is most predictable by the United States trade policy uncertainty. To achieve the study objective, frequency domain causality, wavelet coherence analysis, and time-varying causality are employed in analyzing annual data sets over the period 1990–2019. The summary of the study findings is as follows; first, trade policy uncertainty emanating from the United States significantly predicts Nigeria’s overall integration into global value chains. Second, there is a positive association between Nigeria’s integration into global value chains and the United States trade policy uncertainty. Third, Nigeria’s overall integration into global value chains is highly correlated with the United States trade policy uncertainty in periods around the global economic crisis of 2007/08 and Nigeria’s recession of the late 2010s. Fourth, most of the predictability noticed in the relations between trade policy uncertainty generated by the United States and the overall global value chain participation is caused by the relations between the United States trade policy uncertainty and Nigeria’s forward linkage into global value chain participation.