The study looked at 91 trade agreements since 1980 to see if countries give trade benefits in return for receiving them. They found that in agreements between similar countries, there is a clear give-and-take, but this is less common in agreements between rich and poor countries. Larger countries tend to get more concessions from smaller ones. Overall, the research suggests that it's better for countries to open up their markets without expecting much in return, as the long-term benefits of free trade outweigh any short-term gains from using protection as a bargaining tool.