how do you find the line of best fit 
there are several approaches to estimating a line of best fit to some data the simplest and crudest involves visually estimating such a line on a scatter plot and drawing it in to your best ability the more precise method involves the least squares method this is a statistical procedure to find the best fit for a set of data points by minimizing the sum of the offsets or residuals of points from the plotted curve this is the primary technique used in regression analysis 