The study looked at how different levels of debt affect the economic growth of advanced countries. They found that having a certain amount of debt doesn't really impact the growth of GDP per person. However, having debt below or above this threshold can actually help boost GDP growth by a small percentage. Other factors like inflation, trade, savings, and government spending also play a role in economic growth. Inflation and trade have positive effects, while savings and investment have a significant positive impact on GDP growth. On the other hand, government spending has a negative effect on economic growth.