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Quadratic Artificial Likelihood Functions Using Estimating Functions
Author(s) -
WANG JINFANG
Publication year - 2006
Publication title -
scandinavian journal of statistics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.359
H-Index - 65
eISSN - 1467-9469
pISSN - 0303-6898
DOI - 10.1111/j.1467-9469.2006.00480.x
Subject(s) - mathematics , likelihood function , function (biology) , quadratic equation , score , quadratic function , estimating equations , likelihood ratio test , statistics , estimation theory , maximum likelihood , geometry , evolutionary biology , biology
. A vector‐valued estimating function, such as the quasi‐score, is typically not the gradient of any objective function. Consequently, an analogue of the likelihood function cannot be unambiguously defined by integrating the estimating function. This paper studies an analogue of the likelihood inference in the framework of optimal estimating functions. We propose a quadratic artificial likelihood function for an optimal estimating function. The objective function is uniquely identified as the potential function from the vector field decomposition by imposing some natural restriction on the divergence‐free part. The artificial likelihood function is shown to resemble a genuine likelihood function in a number of respects. A bootstrap version of the artificial likelihood function is also studied, which may be used for selecting a root as an estimate from among multiple roots to an estimating equation.