An algorithm suggested by Hendry (1999) for estimation in a regression with more regressors than observations, is analyzed with the purpose of finding an estimator that is robust to outliers and structural breaks.  This estimator is an example of a one-step M-estimator based on Huber's skip...

This paper provides a means of accurately simulating explosive autoregressive processes, and uses this method to analyse the distribution of the likelihood ratio test statistic for an explosive second order autoregressive process. Nielsen (2001) has shown that for the asymptotic distribution of...

We undertake a generalization of the cumulative sum of squares (CUSQ) test to the case of non-stationary autoregressive distributed lag models with quite general deterministic time trends.  The test may be validly implemented with either ordinary least squares residuals or standardized...

The classical Chow (1960) test for structural instability requires strictly exogenous regressors and a break-point specified in advance.  In this paper we consider two generalisations, the 1-step recursive Chow test (based on the sequence of studentized recursive residuals) and its supremum...

A vector autoregression is singular when explosive characteristic roots have geometric multiplicity larger than one.  The singular component is a mixingale.  Martingale decompositions are constructed for sample moments involving the singular component.  This permits weak and strong analysis...

Reserving in general insurance is often done using chain-ladder-type methods.  We propose a method aimed at situations where there is a sudden change in the economic environment affecting the policies for all accident years in the reserving triangle.  It is shown that methods for forecasting...

During extreme hyper-inflations productivity tends to fall dramatically.  Yet, in models of money demand in hyper-inflation variables such as real income has been given a somewhat passive role, either assuming it exogenous or to have a negligible role.  In this paper we use an empirical...

We consider forecasting from age-period-cohort models, as well as from the extended chain-ladder model.  The parameters of these models are known only to be identified up to linear trends.  Forecasts from such models may therefore depend on arbitrary linear trends.  A condition for invariant...

We consider the identification problem for the model of Lee and Carter (1992).  The parameters of this model are known only to be identified up to certain transformations.  Forecasts from the model may therefore depend on the arbitrarily chosen identification scheme.  A condition for...

The paper by Atkinson, Riani and Ceroli, henceforth ARC, is concerned with detection of outliers and unsuspected structures which is rather important in practice.  This is done through a Forward Search Algorithm.  The statistical analysis of such algorithms poses many challenging problems, and...