# Source of least square estimator of Poisson parameter [duplicate]

I have $X \sim \text{Poisson}(\theta)$

I need to see how least square estimator of $\theta$ is obtained. Is there anything online showing that?

• This seems to be essentially the same question as this one... in the same class, perhaps? – Glen_b -Reinstate Monica Nov 2 '14 at 3:44
• I did see this one, but it did not really help me. What I want is the proof of the least square estimator of $\theta$ – Günal Nov 2 '14 at 10:25