More advanced technologies demand higher degrees of specialization - and longer chains of production connecting raw inputs to final outputs. Longer production chains are subject to a "weakest link" effect: they are more fragile and more prone to failure. Optimal chain length is determined by the...

This essay reviews progress in empirical economics since Leamer's (1983) critique. Leamer highlighted the benefits of sensitivity analysis, a procedure in which researchers show how their results change with changes in specification or functional form. Sensitivity analysis has had a salutary but...

In a model of evolution driven by conflict between societies more powerful states have an advantage. When the influence of outsiders is small we show that this results in a tendency to hegemony. In a simple example in which institutions differ in their "exclusiveness" we find that these...

Intellectual property (IP) protection involves a trade-off between the undesirability of monopoly and the desirable encouragement of creation and innovation. Optimal policy depends on the quantitative strength of these two forces. We give a quantitative assessment of current IP policies. We...

This paper is a non-technical and somewhat philosophical essay, that seeks to investigate the relationship between economics and reality. More precisely, it asks how reality in the form empirical evidence does or does not influence economic thinking and theory. In particular, which role do...

Many believe that "big data" will transform business, government and other aspects of the economy. In this article we discuss how new data may impact economic policy and economic research. Large-scale administrative datasets and proprietary private sector data can greatly improve the way we...

This chapter provides a selective review of some contemporary approaches to program evaluation. One motivation for our review is the recent emergence and increasing use of a particular kind of "program" in applied microeconomic research, the so-called Regression Discontinuity (RD) Design of...

Two recent papers, Deaton (2009), and Heckman and Urzua (2009), argue against what they see as an excessive and inappropriate use of experimental and quasi-experimental methods in empirical work in economics in the last decade. They specifically question the increased use of instrumental...

This paper develops a decision-theoretic approach to policy analysis. We argue that policy evaluation should be conducted on the basis of two factors: the policymaker's preferences, and the conditional distribution of the outcomes of interest given a policy and available information. From this...

This paper combines different strands of the productivity literature to investigate the effect of idiosyncratic (firm-level) policy distortions on aggregate outcomes. On the one hand, a growing body of empirical research has been relating cross-country differences in key economic outcomes, such...