Structural break tests robust to regression misspecification

Alaa Abi Morshed, E. Andreou, Otilia Boldea

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Structural break tests for regression models are sensitive to model misspecification. We show—analytically and through simulations—that the sup Wald test for breaks in the conditional mean and variance of a time series process exhibits severe size distortions when the conditional mean dynamics are misspecified. We also show that the sup Wald test for breaks in the unconditional mean and variance does not have the same size distortions, yet benefits from similar power to its conditional counterpart in correctly specified models. Hence, we propose using it as an alternative and complementary test for breaks. We apply the unconditional and conditional mean and variance tests to three US series: unemployment, industrial production growth and interest rates. Both the
unconditional and the conditional mean tests detect a break in the mean of interest rates. However, for the other two series, the unconditional mean test does not detect a break, while the conditional mean tests based on dynamic regression models occasionally detect a break, with the implied break-point estimator varying across different dynamic specifications. For all series, the unconditional variance does not detect a break while most tests for the conditional variance do detect a break which also varies across specifications.
Original languageEnglish
Article number27
Number of pages39
JournalEconometrics
Volume6
Issue number2
DOIs
Publication statusPublished - Jun 2018

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Misspecification
Structural break tests
Wald test
Interest rates
Size distortion
Regression model
Unemployment
Industrial production
Estimator
Model misspecification
Conditional variance

Keywords

  • structural change; sup Wald test; dynamic misspecification

Cite this

Abi Morshed, Alaa ; Andreou, E. ; Boldea, Otilia. / Structural break tests robust to regression misspecification. In: Econometrics. 2018 ; Vol. 6, No. 2.
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Structural break tests robust to regression misspecification. / Abi Morshed, Alaa; Andreou, E.; Boldea, Otilia.

In: Econometrics, Vol. 6, No. 2, 27, 06.2018.

Research output: Contribution to journalArticleScientificpeer-review

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AB - Structural break tests for regression models are sensitive to model misspecification. We show—analytically and through simulations—that the sup Wald test for breaks in the conditional mean and variance of a time series process exhibits severe size distortions when the conditional mean dynamics are misspecified. We also show that the sup Wald test for breaks in the unconditional mean and variance does not have the same size distortions, yet benefits from similar power to its conditional counterpart in correctly specified models. Hence, we propose using it as an alternative and complementary test for breaks. We apply the unconditional and conditional mean and variance tests to three US series: unemployment, industrial production growth and interest rates. Both theunconditional and the conditional mean tests detect a break in the mean of interest rates. However, for the other two series, the unconditional mean test does not detect a break, while the conditional mean tests based on dynamic regression models occasionally detect a break, with the implied break-point estimator varying across different dynamic specifications. For all series, the unconditional variance does not detect a break while most tests for the conditional variance do detect a break which also varies across specifications.

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