The article examines how trade liberalization affects economic activity by studying a model with different productivity levels among businesses and costs of exporting. By comparing the model to real data, the researchers find that reducing tariffs leads to significant benefits, even though the gains may be smaller in models with fixed export costs. They also discover that after trade reforms, economic activity can exceed its normal level before stabilizing, with the peak occurring about 10 years later. This suggests that trade liberalization can have long-lasting effects on the economy.