# Minimum Variance Unbiased Estimator of Poisson

Let $$X1,X2,.....,Xn$$ be iid Poisson random variables with unknown parameter $$p>0$$. Find the minimum variance unbiased estimator of $$e^(-2p)$$.

I could find two estimators, one by the method of the Cramer Rao and another method by the MLE, do I compare only the MLEs of the two method. Also, the cramer rao lower bound for variance in this case is not achieved.