The article explores different interest rate patterns in Denmark, Germany, Sweden, and the UK. By using a method called generalized method of moments (GMM), the researchers found that interest rate levels and volatility are related in some countries. They also discovered that interest rates tend to revert to a mean value over time. The study suggests that the models created are good at predicting real-world data. Additionally, a significant change in the Danish interest rate process was observed in August 1985, possibly due to a shift in monetary policy.