Hostname: page-component-5c6d5d7d68-xq9c7 Total loading time: 0 Render date: 2024-08-09T11:37:13.794Z Has data issue: false hasContentIssue false

THE REAL PART OF A COMPLEX ARMA PROCESS

Published online by Cambridge University Press:  05 April 2007

Ralph W. Bailey
Affiliation:
University of Birmingham

Abstract

In what follows all processes referred to are weakly stationary. Let us call the real part of a complex ARMA(p,q) process a Re CARMA(p,q) process. Every real ARMA(p,q) process can trivially be written as a Re CARMA(p,q) process. Provided the moment properties of complex linear processes are appropriately specified, the following inverse result is available: every Re CARMA(p,q) process is spectrally equivalent to a real ARMA(2p,p + q) process or some simpler process. Thus the ARMA and Re CARMA classes are spectrally equivalent. The question of whether an ARMA or a Re CARMA parametrization is better in a given context then arises. If cyclicality is present, and especially if we wish to treat cycles, growth, and decay together, in a model whose parameters are easy to interpret, then a Re CARMA approach may be helpful.The author thanks Paolo Paruolo, A.M. Robert Taylor, and an anonymous referee for helpful suggestions.

Type
NOTES AND PROBLEMS
Copyright
© 2007 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Bell, E.T. (1945) The Development of Mathematics, 2nd ed. McGraw-Hill.
Brockwell, P.J. & R.A. Davis (1987) Time Series: Theory and Models. Springer-Verlag.
Granger, C.W.J. & M.J. Morris (1976) Time series modelling and interpretation. Journal of the Royal Statistical Society, Series A 139, 246257.Google Scholar
Harvey, A.C. (1989) Forecasting, Structural Time Series Models and the Kalman Filter. Cambridge University Press.