Regression line (1 of 2)

A regression line is a line drawn through a scatterplot of two variables. The line is chosen so that it comes as close to the points as possible. The plot shown below is based on the following data:

 X     Y      Y'    Y-Y'    (Y-Y')²
 2     5     4.8     .2      .04
 3     6     6.6    -.6      .36
 4     9     8.4     .6      .36
 5    10    10.2    -.2      .04

The four (X,Y) pairs found in the first two columns of the table are indicated in the plot as the four points. The line in the plot is the best fitting straight line; it has a slope of 1.8 and a Y-intercept of 1.2. Y' represents values along this regression line. The general formula for Y' is: Y' = bX + A where b is the slope and A is the Y intercept.