# Homework Help: MLE of Poisson dist

1. Nov 19, 2012

### mrkb80

1. The problem statement, all variables and given/known data
Let $X_1,...,X_n$ be a random sample from a poisson distribution with mean $\lambda$

Find the MLE of $\lambda^2 + 1$

2. Relevant equations

3. The attempt at a solution

I found $\hat{\lambda}=\bar{x}$

Can I just square it and add 1 and solve for lambda hat?

If not I have no idea how I would get the FOC (with respect to $\lambda^2 + 1$)

of the log-likelihood function $\ln{L(\lambda^2+1)}=-n\lambda + \Sigma_{i=1}^n x_i \ln{\lambda} - \ln{\Pi_{i=1}^n x_i!}$

2. Nov 19, 2012

### haruspex

That's my understanding of how MLE works. If α is the value of λ that maximises the likelihood of the observed data, then (α2+1) must be the value of λ2+1 that does the same.

3. Nov 19, 2012

### mrkb80

cool. thanks again.