The researchers developed a new economic model to replace the widely used Cobb-Douglas function. This new model better explains fluctuations in GDP and is more reliable than the old one. The new model sees installed capacity as a sunk cost generating economic rents, rather than aggregate capital. The analysis of U.S. growth data from 1949 to 2008 showed that the new model explains 85% of GDP fluctuations, while the old model was not as effective. This challenges the idea of using value-weighted capital aggregates to explain production and suggests a different way to understand how monetary policy affects productivity.