4. Best Linear Unbiased Estimator (BLUE) If an estimator is linear. is unbiased and has a minimum variance in the class of all linear unbiased estimators of a parameter, it is called a best linear unbiased estimator 5. Consistency x=∑ x=∑ X n+1 E(X=uy (X)=-14 +1 An estimator (e.g, X*) is said to be a consistent estimator if it approaches the true value of the parameter as the sample size gets larger and larger4. Best Linear Unbiased Estimator(BLUE) If an estimator is linear, is unbiased, and has a minimum variance in the class of all linear unbiased estimators of a parameter, it is called a best linear unbiased estimator. 5. Consistency An estimator (e.g., X*) is said to be a consistent estimator if it approaches the true value of the parameter as the sample size gets larger and larger. =  n X X i  + = n 1 X X i E X =  X ( ) X n n E X       + = 1 ( ) *