Weak Consistency of the MLE
Let (R, {Pθ}θ∈R) denote a statistical model associated with a statistical experiment X1,...,Xn ∼ iid Pθ* for some true parameter θ* that we would like to estimate. You construct the maximum likelihood estimator θ̂MLEn for θ*. Which of the following conditions is not necessary for the MLE θ̂MLEn to converge to θ* in probability?
The model (R, {Pθ}θ∈R) is identified. (Recall that the parameter θ is identified if the map θ ↦ Pθ is injective.)
For all θ ∈ Θ, the support of Pθ does not depend on θ.
The MLE θ̂MLEn is given by the sample average.
The Fisher information I(θ) is non-zero in an interval containing the true parameter θ*. (Note that this is what it means for a 1x1 matrix, a scalar, to be invertible.)