In the paper we consider the role of seasonal intercepts in seasonal cointegration analysis. For the nonseasonal unit root, such intercepts can generate a stochastic trend with a drift common to all observations. For the seasonal unit roots, however, we show that unrestricted seasonal intercepts...

In this paper we investigate the properties of the Lagrange Multiplier (LM) test for autoregressive conditional heteroskedasticity (ARCH) and generalized ARCH (GARCH) in the presence of additive outliers (AO's). We show analytically that both the asymptotic size and power are adversely affected...

The popular 'airline' model for a seasonal time series assumes that a variable needs double differencing, i.e. first and seasonal (or annual) differencing. The resultant time series can usaually be described by a low order moving average model with estimated roots close to the unit circle. This...

Standard unit root tests and cointegration tests are sensitive to atypical events such as outliers and structural breaks. This paper uses outlier robust estimation techniques to reduce the impact of these events on cointegration analysis. As a byproduct of computing the robust estimator, we...

To understand the relevance of marketing efforts, it has become standard practice to estimatethe long-run and short-run effects of the marketing-mix, using, say, weekly scanner data. Acommon vehicle for this purpose is an econometric time series model. Issues that areaddressed in the literature...

Unit root tests and cointegration tests are sensitive to atypical events as outliers and structural breaks. This paper uses outlier robust estimation techniques to reduce the impact of these events on cointegration analysis. As a byproduct of computing the robust estimator, we obtain weights for...