Chapter 1 Business cycle fluctuations in us macroeconomic time series This chapter examines the empirical relationship in the postwar United States between the aggregate business cycle and various aspects of the macroeconomy such as production interest rates prices productivity sectoral employment investment income and consumption. This is done by examining the strength of the relationship between the aggregate cycle and the cyclical components of individual time series whether individual series lead or lag the cycle and whether individual series are useful in predicting aggregate fluctuations. The chapter also reviews some additional empirical regularities in the US economy including the Phillips curve and some long run relationships in particular long run money demand long run properties of interest rates and the yield curve and the long run properties of the shares in output of consumption investment and government spending.