In: Statistics and Probability
In estimating the average price of a gallon of gasoline in a
region we plan to select a random sample (independent and
identically distributed) of size 10. Let X1,
X2, ... , X10 denote the selected sample. The
two estimators for estimating the average price, μ, are:
U1 = (X1 + X2 + X3 +
X4 + X5 + X6 + X7 +
X8 +X9 + X10)/10
U2 = (X1 + X2 + X3 +
X4 + X5 + X6 + X7 +
X8 )/8 + X1 - X2 .
a. (6 points) which of the above estimators are unbiased? Fully
justify your answer.
b. (14 points) Using the mean square error criterion, determine
which estimator is better.