# What is the standard error of an estimator?

The standard error of estimate of Y on X is ${S}_{Y X}$ = sqrt $\sum$ (y - $\hat{y}$)^2$=$sqrt {sum[ (y - bary- ${b}_{y x}$ (x - $\overline{x}$ )]^2= ${\sigma}_{y}$ sqrt(1 - r^2 )
The regression equation of Y on X is given by $\hat{y}$ = $\overline{y}$ + ${b}_{y x}$ (x - $\overline{x}$ )