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MLE's bias pathology, Fisher's Specification Problem and Model Corrected Maximum Likelihood Estimates (MCMLE)

Abstract

MLE's inherent bias pathology that is confirmed herein for models with unknown parameters θ,ψ\theta,\psi and MLE ψ^\hat \psi function of MLE θ^\hat \theta and the need for model accuracy in Fisher's specification problem suggest updating the Likelihood Equation to be solved for ψ\psi using the model of the data Y in it with θ^\hat \theta replacing θ.\theta. For several models the so-obtained Model Corrected MLE ψ^MC\hat \psi_{MC} reduces either totally or partially the bias when estimating shape parameters. For the Pareto model in particular, with parameters θ\theta and ψ\psi both unknown, ψ^MC\hat \psi_{MC} reduces the bias but also the variance of ψ^.\hat \psi. The results contribute in the explanation of the "difference" that has puzzled R. A. Fisher.

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