The study looked at economic fluctuations in 21 countries to see if they were caused by temporary changes in demand or more permanent shifts in supply. They found that both types of disturbances play a significant role in affecting economic growth and inflation. Among the G7 countries, the UK and US are most affected by demand shocks, while Japan and Germany are least affected. The study also showed a decline in the rate of increase in supply potential over time, which supports the idea of post-war economic growth theory.