The empirical finding that exporting firms are more productive on average than non-exporters has provoked a large theoretical literature based on models such as Melitz (2003), where more productive firms are more likely to overcome costs associated with trade. This paper provides a systematic empirical assessment of the Melitz framework using a unique Irish dataset that includes information on destinations and firm characteristics such as productivity. We find a number of interesting deviations from the model's predictions including a high degree of unpredictable idiosyncratic participation in export markets by firms, a relatively weak positive correlation between the extent of export participation and export sales, and a limited role for productivity in explaining firm exporting behavior. We illustrate the effect of firm heterogeneity on gravity regressions of aggregate trade flows and show how past exporting to a particular market has a strong impact on the current probability of exporting there.
