Sorry about the naff title, couldn't think of anything else. So this question's on a past exam paper...

Suppose $\displaystyle T$ is to be used as an estimator for a parameter $\displaystyle \theta$. Describe five criteria you would use to judge whether $\displaystyle T$ is a good estimator of $\displaystyle \theta$.

So I have these five criteria written down:Is that what the question's getting at?

Unbiasedness;or, on average, the estimator is correct.Efficiency;or the estimator has a small variance.Consistency;where larger samples give more precise estimates i.e. $\displaystyle E[T]\rightarrow\mu$ and $\displaystyle Var(T)\rightarrow0$ as $\displaystyle n\rightarrow\infty$Robustness/resistance;where the estimator will perform well even if the model isn't quite correct or there are outlying values in the data.Ease of calculation;since an estimator is more preferable if it is easy to calculate and understand.