3
$\begingroup$

Following this question:Why the Pitman estimator is given by the sample mean of X and Y?.

Let $X_1, \dots ,X_n$ be i.i.d. random variables having distribution $P(X_j = \theta) = P(X_j = θ + 1) =1/2,$ where $\theta\in Z$ is an integer valued unknown location parameter. Find the minimum risk location equivariant estimator of $\theta$ for the squared error loss function.


It seems that the answer is the median of $\{X_1,\dots, X_n\}$. I try to get the posterior distribution of $\theta$ but I cannot do that. The likelihood function $$ L(\theta, X)=\prod_{i=1}^n p(X_i|\theta)=? $$

It seems that the posterior distribution is also maximized when $\theta$ is equal to the most common value among the $X_i$. Therefore, the minimum risk location equivariant estimator is $\hat{\theta}=mode\{X_1,\dots,X_n\}$.

$\endgroup$
2
  • $\begingroup$ Note that you are supposed to find the MRLE estimator for the squared error loss function, not the maximum a posteriori estimator. $\endgroup$
    – jbowman
    Commented Jul 7, 2023 at 16:00
  • $\begingroup$ @jbowman Thanks. So what do I need to do? $\endgroup$
    – Hermi
    Commented Jul 7, 2023 at 16:01

0

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Browse other questions tagged or ask your own question.