An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
The problem of initializing the Kalman filter for nonstationary time series models is considered. Ansley and Kohn (1985a) and Kohn and Ansley (1986) develop a "modified Kalman filter" for use with nonstationary models to produce estimates from what they call a "transformation approach". We show the same results can be obtained with a suitable initialization of the ordinary Kalman filter. Assuming there are d starting values for the nonstationary series, we initialize the Kalman filter using data through time d with the transformation approach estimate of the state vector and its associated error covariance matrix at time d. We give details of the initialization for ARIMA models, ARIMA component models, and dynamic linear models. We present an example to illustrate how the results may differ from results obtained under more naive initializations that have been suggested.
Share
Related Information
Some content on this site is available in several different electronic formats. Some of the files may require a plug-in or additional software to view.
Top