• E32;
  • E47;
  • E52;
  • E58
  • inflation;
  • Phillips correlation;
  • frequency domain;
  • cross-spectral analysis;
  • band-pass filter;
  • complex demodulation

We use complex demodulation techniques to investigate changes in the correlation between real activity and inflation at the business-cycle frequencies in the United States, the United Kingdom, the Eurozone, and 10 other Organization for Economic Cooperation and Development (OECD) countries over the post-WWII era. Consistent with the analysis of Ball, Mankiw, and Romer (1988) we document a positive correlation between the time-varying average gain of real activity onto inflation at the business-cycle frequencies and inflation's Hodrick-Prescott trend, which is compatible with New Keynesian theories emphasizing the link between trend inflation, the frequency of price adjustments, and the slope of the Phillips trade-off.