Manuscript submitted to The Econometrics Journal, pp. 1{45. Machine Learning and Structural Econometrics: Contrasts and Synergies Fedor Iskhakovy and John Rustz and Bertel Schjerningzz yAustralian National University, 1018 HW Arndt bld., Kingsley Pl, Acton ACT 2601, Australia E-mail:
[email protected] zCorresponding Author: Georgetown University, 583 Intercultural Center, Washington DC 20057-1036, USA E-mail:
[email protected] zzUniversity of Copenhagen, Øster Farimagsgade 5, bld. 25 1353 Copenhagen K, Denmark E-mail:
[email protected] Summary We contrast machine learning (ML) and structural econometrics (SE), focusing on areas where ML can advance the goals of SE. Our views have been informed and in- spired by the contributions to this special issue and papers presented at the second conference on Dynamic Structural Econometrics at the University of Copenhagen in 2018 \Methodology and applications of structural dynamic models and machine learn- ing". ML offers a promising class of techniques that can significantly extend the set of questions we can analyze in SE. The scope, relevance and impact of empirical work in SE can be improved by following the lead of ML by questioning and relaxing the as- sumption of unbounded rationality. However, for the foreseeable future ML is unlikely to replace the essential role of human creativity and knowledge in model building and inference, particularly with respect to the key goal of SE, counterfactual prediction. Keywords: Machine learning, structural econometrics, curse of dimensionality, bounded rationality, counterfactual predictions The best way for machines to learn is to stand on the shoulders, not the toes, of their human teachers.