Question

Which of the following does not belong?

the average of a variable for population

the mean of a variable for population

the expected value of a variable for a population

all of the above are equivalent

Answer 1

All of them are equivalent.

Average Value = Mean Value = Expected Value

Avg and mean are equivalent terms i.e saying avg of a variable is same as mean of that variable where as expected value is unbiased estimator of mean value. Hence, all of them are equivalent for a population.

However expected value and mean value differs for a sample, i.e for different samples there may be different expected value which will not match with expected value/mean of population.But for a population they are equal.