A common finding in the empirical literature is that financial volatility exhibits high persistence, or slow mean reversion of the order of months. We present evidence that financial volatility data contains more than a single time scale. After showing that the expectation of the sum of the...

We use realized volatility to study the influence of central bank interventions on the yen/dollar exchange rate. Realized volatility is a technical innovation that allows specifying a system of equations for returns, realized volatility, and interventions without endogeneity bias. We find that...

We study the simultaneous occurrence of long memory and nonlinear effects, such as structural breaks and thresholds, in autoregressive moving average (ARMA) time series models and apply our modeling framework to series of daily realized volatility. Asymptotic theory for the quasi-maximum...

This article shows that bagging can improve the forecast accuracy of time series models for realized volatility. We consider 23 stocks from the Dow Jones Industrial Average over the sample period 1995 to 2005 and employ two different forecast models, a log-linear specification in the spirit of...

We study the stability of estimated linear statistical relations of global mean temperature and global mean sea level with regard to data revisions. Using four different model specifications proposed in the literature, we compare coefficient estimates and long-term sea level projections using...

Mean reversion, volatility persistence, long memory, time scales, stochastic volatility, GARCH, spurious long memory. - I discuss mean reversion in the first and the second moment of the return distribution. After a discussion of the concepts and a summary of the findings in the literature, I...