Abstract
In this paper the problem of estimating the ratio of variances, σ, in a bivariate normal distribution with unknown mean is considered from a decision-theoretic point of view. First, the UMVU estimator of σ is derived, and then it is shown to be inadmissible under two specific loss functions, namely, the squared error loss and the entropy loss. The derivation of the results is done by conditioning on an auxiliary negative binomial random variable.
Similar content being viewed by others
References
Brewster, J. F. and Zidek, J. V. (1974). Improving on equivariant estimators, Ann. Statist., 2, 21-38.
Finney, D. J. (1938). The distribution of the ratio of estimates of the two variances in a sample from a normal bivariate population, Biometrika, 30, 190-192.
Gelfand, A. E. and Dey, D. K. (1988). On the estimation of a variance ratio, J. Statist. Plann. Inference, 19, 121-131.
Ghosh, M. and Kundu, S. (1996). Decision theoretic estimation of the variance ratio, Statist. Decisions, 14, 161-175.
Iliopoulos, G. and Kourouklis, S. (1999). Improving on the best affine equivariant estimator of the ratio of generalized variances, J. Multivariate Anal., 68, 176-192.
Iliopoulos, G. and Kourouklis, S. (2000). Interval estimation for the ratio of scale parameters and for ordered scale parameters, Statist. Decisions, 18, 169-184.
Kubokawa, T. (1994). Double shrinkage estimation of ratio of scale parameters, Ann. Inst. Statist. Math., 46, 95-116.
Kubokawa, T. and Srivastava, M. S. (1996). Double shrinkage estimators of ratio of variances, Multidimensional Statistical Analysis and Theory of Random Matrices (eds. A. K. Gupta and V. L. Girko), 139-154, VSP, Netherlands.
Madi, T. M. (1995). On the invariant estimation of a normal variance ratio, J. Statist. Plann. Inference, 44, 349-357.
Morgan, W. A. (1939). A test for the significance of the difference between the two variances in a sample from a normal bivariate population, Biometrika, 31, 13-19.
Nagata, Y. (1989). Improvements of interval estimations for the variance and the ratio of two variances, J. Japan Statist. Soc., 19, 151-161.
Pitman, E. J. G. (1939). A note on normal correlation, Biometrika, 31, 9-12.
Stein, C. (1964). Inadmissibility of the usual estimator for the variance of a normal distribution with unknown mean, Ann. Inst. Statist. Math., 16, 155-160.
Author information
Authors and Affiliations
About this article
Cite this article
Iliopoulos, G. Decision Theoretic Estimation of the Ratio of Variances in a Bivariate Normal Distribution. Annals of the Institute of Statistical Mathematics 53, 436–446 (2001). https://doi.org/10.1023/A:1014600625165
Issue Date:
DOI: https://doi.org/10.1023/A:1014600625165