A line of best fit can be roughly determined using an eyeball method by drawing a straight line on a scatter plot so that the number of points above the line and below the line is about equal (and the line passes through as many points as possible).
It is used to study the nature of relation between two variables. The line of best fit in the scatter plot above rises from left to right; so, the variables have a positive correlation . Here, the line of best fit drops from left to right, so the variables have a negative correlation.
