The article looks at how well countries trade with each other globally by using a formula called the "gravity equation." Normally, this formula only looks at income and distance to predict trade amounts between countries. The researchers, however, used a different method called "stochastic frontier" to estimate trade efficiencies more accurately. They found out that most countries don't trade as much as they could. The estimated trade amounts were much higher than the actual trade happening between countries, meaning many countries are not as efficient as they could be in international trade. They ranked countries and regions based on their trade efficiencies.