Economists are interested in the choices people make when they shop, when they choose jobs, and when they vote, as well as the choices made in state capitols, at the Federal Reserve, and on Wall Street. Understanding the sources of economic growth, differences in income across countries, rate of inflation, and the appropriate policy responses to recessions are fundamental issues in macroeconomics, which is the study of the performance of an economy as a whole. Microeconomists study households, firms, and markets.