The Armington elasticity, which measures how easily goods from different countries can be substituted for each other, is a key factor in international economics. Researchers used a model with nested CES preferences to study this elasticity. They looked at both macro and micro elasticities using simulated data and real U.S. production and trade data. They found that in about half of goods, there is no significant difference between the two elasticities. However, in the other half, the macro elasticity is significantly lower than the micro elasticity, even when estimated at the same level of detail.