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On the Existence and Application of Continuous-Time Threshold Autoregressions of Order Two
Published online by Cambridge University Press: 01 July 2016
Abstract
A continuous-time threshold autoregressive process of order two (CTAR(2)) is constructed as the first component of the unique (in law) weak solution of a stochastic differential equation. The Cameron–Martin–Girsanov formula and a random time-change are used to overcome the difficulties associated with possible discontinuities and degeneracies in the coefficients of the stochastic differential equation. A sequence of approximating processes that are well-suited to numerical calculations is shown to converge in distribution to a solution of this equation, provided the initial state vector has finite second moments. The approximating sequence is used to fit a CTAR(2) model to percentage relative daily changes in the Australian All Ordinaries Index of share prices by maximization of the ‘Gaussian likelihood'. The advantages of non-linear relative to linear time series models are briefly discussed and illustrated by means of the forecasting performance of the model fitted to the All Ordinaries Index.
Keywords
- Type
- General Applied Probability
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- Copyright
- Copyright © Applied Probability Trust 1997
Footnotes
Research supported in part by NSF Grant DMS 9504596 and GER 9023335.
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