# Thread: can any1 prove that equality

1. ## can any1 prove that equality

SE = SD(of the population)/sqrt(n)

SE: standard error of the mean. n is population size.

why is that true . i wanna know either statistical reason or mathematical reason.

2. Originally Posted by bogazichili
SE = SD(of the population)/sqrt(n)

SE: standard error of the mean. n is population size.

why is that true . i wanna know either statistical reason or mathematical reason.
Read this: Sampling Distribution of the Mean

3. Just take the square root of...

$V(\bar X) =V\biggl({X_1+\cdots +X_n\over n}\biggr)={1\over n^2}\bigl[ V(X_1)+\cdots +V(X_n)\bigr] ={1\over n^2}[n\sigma^2]={\sigma^2\over n}$