The study looked at how a specific rule could explain the Fed's monetary policy in the 1920s and 1930s. They found that a modified Taylor rule, which adjusts based on economic conditions, was better at capturing the Fed's actions during this time. The researchers discovered that the rule needed to be nonlinear, meaning it only activated under certain conditions, to accurately reflect the Fed's behavior. This new approach provided insights into how monetary policy was managed during the interwar period and offered valuable information for understanding historical monetary regimes.