Estimator
used in mathematical statistics to determine an estimated value / From Wikipedia, the free encyclopedia
In statistics, an estimator is a rule for calculating an estimate of a given amount based on observed data. The rule (the estimator), the amount that is being measured (the estimand) and its result (the estimate) are different.[1]
An estimator of a parameter is often written as .[2] If the expected value of the estimator is equal to the parameter, then the estimator is called unbiased. Otherwise, it is called biased.[3]