Say we are given an exponential distribution. This questions first asks you to find the MLE of $\theta$ an exponential distribution which I found to be equal to $\bar{X}$. Then it asks you to compute the Mean Squared Error? I have no idea how to do it. I've been given the formula where it is equal to $\operatorname{Var}(T) + \operatorname{Bias}(T)^2$ but I am unsure of what it means. In the solution of the question it says that the bias is equal to $0$, but where does that come from?
How can I know when a bias is equal to $0$, and when it isn't? Again, why is the bias $0$ in this case?
