why the sum of residuals must always equal zero?

#1
Hello,

I was wondering why the sum of the residuals of a simple regression line must always equal zero. It simply blows my mind that it could always be true. Please help me wrap my mind around this concept.

Thanks:D,
MofB
 

Dason

Ambassador to the humans
#4
Uh... That's pretty much one of the only terms that doesn't evaluate to 0. \(\sum(x_i - \bar{x})\) is 0 though so when you multiply r(sy/sx) by 0 you get 0.