Counting and Locating the Solutions of Polynomial Systems of Maximum Likelihood Equations, II: The Behrens-Fisher Problem

dc.creatorBuot, Max-Louis G.
dc.creatorHosten, Serkan
dc.creatorRichards, Donald St. P.
dc.date2007-09-06
dc.date.accessioned2026-07-07T08:28:07Z
dc.date.available2026-07-07T08:28:07Z
dc.descriptionLet $μ$ be a $p$-dimensional vector, and let $Σ_1$ and $Σ_2$ be $p \times p$ positive definite covariance matrices. On being given random samples of sizes $N_1$ and $N_2$ from independent multivariate normal populations $N_p(μ,Σ_1)$ and $N_p(μ,Σ_2)$, respectively, the Behrens-Fisher problem is to solve the likelihood equations for estimating the unknown parameters $μ$, $Σ_1$, and $Σ_2$. We shall prove that for $N_1, N_2 > p$ there are, almost surely, exactly $2p+1$ complex solutions of the likelihood equations. For the case in which $p = 2$, we utilize Monte Carlo simulation to estimate the relative frequency with which a typical Behrens-Fisher problem has multiple real solutions; we find that multiple real solutions occur infrequently.
dc.descriptionTo appear in Statistica Sinica
dc.identifierhttps://arxiv.org/abs/0709.0957
dc.identifierhttp://arxiv.org/abs/0709.0957
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/137503
dc.subjectStatistics Theory
dc.subjectAlgebraic Geometry
dc.subjectComputation
dc.subject62F99; 14Q99
dc.titleCounting and Locating the Solutions of Polynomial Systems of Maximum Likelihood Equations, II: The Behrens-Fisher Problem
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