US monetary policy helped reduce US economic fluctuations and separate household spending from the business cycle. The researchers created a model to study household investment, inflation, and interest rates, with parameters that could change independently. They found that changes in the size of monetary policy shocks affected the correlation between different parts of the economy and their volatility. During periods of high volatility in monetary policy shocks, household investment was closely tied to the business cycle. However, in other periods, monetary policy shocks had little impact on the economy's ups and downs.