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

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

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. and asRobustness/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.