We have two variables X and Y following the linear model
Y = a + bX
where a & b are the parameters.
We have collected the pairs of numerical observations namely
(X1 , Y1) , (X2 , Y2) , (X3 , Y3) , ................... , (Xn , Yn)
on the variables X and Y.
It is natural that the observations are not free from error.
Thus, each of the observations are composed of actual value and error.
In this case, do the above observations on (X , Y) follow the linear model as mentioned above ?
The question here is :
" Do the observations on (X , Y) follow the same linear model which is followed by the variables X & Y ? ".