The study found that capital controls, which are policies that restrict the flow of money in and out of a country, are not changed often and tend to stay in place for a long time. These controls have not been consistently used across different countries or time periods. The researchers created a model that shows the costs of implementing these policies are significant, reducing the benefits of capital controls compared to a scenario without these costs. This suggests that when considering using capital controls, policymakers need to take into account the potential drawbacks of implementing them.