Scattering
q One way to estimate the “badness of fit” is
to calculate the scatter:
     scatter  (Se)0.5
q The relation between the scatter to the line
of regression in the analysis of two
variables is like the relation between  the
standard deviation to the mean in the
analysis of one variable.
q If lines are drawn parallel to the line of
regression at distances equal to ± (Se)0.5
above and below the line, measured in the
y direction, about 68% of the observation
should fall between the two lines.
(Se)0.5