Estimation of the Error Variance after a Preliminary-Test of Homogeneity in a Regression Model with Spherically Symmetric Disturbances

Judith A. Giles

No 262937, Department of Economics Discussion Papers from University of Canterbury - New Zealand

Abstract: In this paper we consider the risk (under quadratic loss) of an estimator cf the error variance after a pre-test for homogeneity of the variances in the two-sample linear regression model. We investigate the effects on risk of assuming normal disturbances when in fact the error distribution is spherically symmetric. We also broaden the standard assumption that the never-pool variance estimators are based on the least squares principle. Using the special case of multivariate Student-t regression disturbances as an illustration, our results show that in some situations we should always pre-test, even if the error variances are equal, and we provide the optimal test critical value. The evaluations also show that using the least squares technique to form the never-pool estimators may not always be the preferred strategy.

Keywords: Agribusiness; Financial Economics (search for similar items in EconPapers)
Pages: 24
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Persistent link: https://EconPapers.repec.org/RePEc:ags:canzdp:262937

DOI: 10.22004/ag.econ.262937

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