This paper analyses the contribution of various numerical approaches to making the estimation of threshold autoregressive time series more efficient. It relies on the computational advantages of QR factorizations and proposes Givens transformations to update these factors for sequential LS...

This paper assesses empirically two competing unemployment theories. It identifies one structural break in U.K. and German unemployment around 1980 that is more severe in both absolute and relative terms than that for the United States in 1973. This offers support for the structuralist theory. A...

Using threshold autoregressive specifications, this paper develops new parametric tests for level asymmetries. It proposes bootstrap likelihood ratio statistics to test the symmetric adjustment null against sign and amplitude asymmetries or a combination of both. Monte Carlo simulations show...