Let the tree decide: FABART. A non-parametric factor model for nonlinear oil shock transmission

The question of how oil supply news shocks transmit to real activity, financial conditions, and regional labor markets is back at the center of the macroeconomic research agenda. To answer this question, we introduce the Factor Bayesian Additive Regression Tree (FABART) model, a nonlinear factor-augmented vector autoregression model, and apply it to a large U.S. macro-financial dataset with externally identified oil supply news shocks. The framework combines a large macro-financial information set with a flexible nonparametric measurement equation, allowing nonlinear transmission to emerge from the data rather than being imposed through a pre-specified functional form. We find that adverse oil supply news shocks generate stronger and more persistent contractions in real activity than the expansions associated with favorable shocks of comparable magnitude, with especially pronounced differences in industrial production, financial variables, and equity prices. Employment responses are highly heterogeneous across U.S. states, with substantially stronger contractions in manufacturing-intensive regions, while energy-producing states display partially offsetting dynamics following adverse oil supply news shocks. Across shock magnitudes, nonlinearities arise mainly between very small and moderate oil-price movements: small shocks generate weak and imprecisely estimated responses, while moderate shocks already produce economically meaningful effects on industrial production and regional employment. Larger shocks do not systematically generateproportionally stronger responses across variables and shock signs. JEL Classification: C11, C32, E32, Q43