# Math Help - How to find residual?

1. ## How to find residual?

what do they mean by residual(y value above minus equation y value. when
1. x is 0.5 and y is 1.6

2. Originally Posted by nppatel4428
what do they mean by residual(y value above minus equation y value. when
1. x is 0.5 and y is 1.6
The residual in a regression model is the difference between the observed and the predicted $y$ for some $x$ ( $y$ the dependent variable and $x$ the independent variable).

So if we have a model $y=a x + b$, and a data point $(x_i,y_i)$ the residual is for this point is:

$r_i=y_i - (a x_i + b)$

RonL