We address the issue of time varying persistence of shocks to macroeconomic time series variables by proposing a new and parsimonious time series model. Our model assumes that this time varying persistence depends on a linear combination of lagged explanatory variables, where this combination...

In this paper we propose a sequential testing approach for a structural change in the variance of a time series, which amounts to a procedure with a controlled asymptotic size as we repeat the test. Our approach builds on that taken in Chu, Stinchcombe and White (1996) for structural change in...

In this paper we consider forecasting daily exchange rate returns using neutral network models (NNs). Based on simulations, we argue (i) that neglected GARCH does not lead to spuriously successful NNs and (ii) that if there is nonlinearity in the conditional mean, NNs will exploit this for...

In this paper we consider empirical econometric models for nine brands of a fast-moving nondurable consumer product using weekly observed scanning data on market share and distribution conditional on advertising, price, promotion activities. Since the data show nonstationary characteristics, we...

In this paper we measure the extent to which countries are converging in per capita productivity levels. We formally define convergence in a time series analytical context, derive the necessary and sufficient conditions and introduce a cluster analytical procedure that enables us to distinguish...

In this paper we examine the interaction between data transformation and the empirical evidence obtained when testing for (non-)linearity. For this purpose we examine nonlinear features in 64 monthly and 53 quarterly US macroeconomic variables for a range of Box-Cox data transformations. Our...

A key application of long memory time series models concerns inflation. Long memory implies that shocks have a long-lasting effect. It may however be that empirical evidence for long memory is caused by neglecting one or more level shifts. Since such level shifts are not unlikely for inflation,...