Adaptive Estimation of Autoregressive Models with Time-Varying Variances

Stable autoregressive models are considered with martingale differences errors scaled by an unknown nonparametric time-varying function generating heterogeneity. An important special case involves structural change in the error variance, but in most practical cases the pattern of variance change ove...

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Bibliographic Details
Main Authors: XU, Ke-Li, PHILLIPS, Peter C. B.
Format: text
Language:English
Published: Institutional Knowledge at Singapore Management University 2008
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Online Access:https://ink.library.smu.edu.sg/soe_research/288
https://ink.library.smu.edu.sg/context/soe_research/article/1287/viewcontent/Adaptive_Estimation_of_Autoregressive_Models_2008.pdf
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Institution: Singapore Management University
Language: English
Description
Summary:Stable autoregressive models are considered with martingale differences errors scaled by an unknown nonparametric time-varying function generating heterogeneity. An important special case involves structural change in the error variance, but in most practical cases the pattern of variance change over time is unknown and may involve shifts at unknown discrete points in time, continuous evolution or combinations of the two. This paper develops kernel-based estimators of the residual variances and associated adaptive least squares (ALS) estimators of the autoregressive coefficients. Simulations show that efficiency gains are achieved by the adaptive procedure.