The article looked into what influences trade between European Union countries. It used a gravity model with data from multiple time points to figure out how different factors affect trade volume. The research showed that the size and economic strength of countries, along with factors like how open they are to trading with other nations, play a big role in determining how much they trade with each other. They also found that the farther countries are from each other, the less they tend to trade. Overall, the study confirmed that how big a country is, how developed it is economically, and how willing it is to trade with others all impact how much it trades with its European Union partners.