We consider the problem of estimating a p-dimensional parameter y ΒΌ Γ°y 1 ; y; y p Γ when the observation is a p ΓΎ k vector Γ°X ; UΓ where dim X ΒΌ p and where U is a residual vector with dim U ΒΌ k: The distributional assumption is that Γ°X ; UΓ has a spherically symmetric distribution around Γ°y; 0Γ: Tw
Estimation of a parameter vector restricted to a cone
β Scribed by Idir Ouassou; William E. Strawderman
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 117 KB
- Volume
- 56
- Category
- Article
- ISSN
- 0167-7152
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β¦ Synopsis
We study estimation of a location vector restricted to a convex cone when the dimension, p, is at least 3. We ΓΏnd estimators which improve on the "usual" estimator (the MLE in the normal case) in the general case of a spherically symmetric distribution with unknown scale. The improved estimators may be viewed as Stein-type shrinkage estimators on the set where the usual unbiased estimator (in the unrestricted case) satisΓΏes the restriction. The improved procedures have the extremely strong property of improving on the "usual" estimator uniformly and simultaneously for all spherically symmetric distributions.
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