Volatility breaks are tested and documented for 19 important monthly macroeconomic time series across the G7 countries. Across all conditional mean specifications considered, including both linear and nonlinear models with and without a structural break, volatility breaks are found to be...

We test for a change in the volatility of 215 US macroeconomic time series over the period 1960-1996. We find that about 90\% of these series have experienced a break in volatility during this period. This result is robust to controlling for instability in the mean and business cycle...

The El Niños Southern Oscillations (ENSO) is a periodical phenomenon of climatic interannual variability which could be measured through either the Southern Oscillation Index (SOI) or the Sea Surface Temperature (SST) Index. The main purpose of this paper is to analyze these two indexes in...