In many economic applications, observations are naturally categorized into mutually exclusive and exhaustive groups. For example, individuals can be classified into cohorts and workers are employees of a particular firm. Grouping models are widely used in economics -- for example, cohort models...

Estimates of the elasticity of substitution between domestic and foreign varieties are small in macroeconomic data, and substantially larger in disaggregated studies. This may be an artifact of heterogeneity. We use disaggregated multilateral trade data to structurally identify elasticities of...

This paper presents an empirical examination of the importance of hysteresis in international trade. An econometric model of export determination is developed where the presence of sunk costs causes discontinuous behaviour and hysteresis so that an individual exporter’s decision to stay in or...

Models with externalities have become increasingly popular for studying both long-term growth and business-cycle fluctuations. Externalities can lead to indeterminacy, allowing self-fulfilling expectations to determine the equilibrium. This paper argues that the importance of indeterminacy might...