The study looked at how changes in government spending and income transfers affect the economy in the United States. By analyzing data on social security benefits and government spending, the researchers found that increasing government spending has a moderate impact on the economy, with a multiplier effect between 0 and 1. On the other hand, raising income transfers, like social security benefits, has a stronger impact, generating a multiplier effect above 1. This means that changes in different types of public expenditure have varying effects on the overall economy.