xkcd #2048 is exceptionally relevant to this. Doing linear regression well with a big dataset is difficult! I do this all the time at work and honestly I often show a scatter plot without any ...

First, show you how to do linear regression in google docs (trendline). Second, I will show you how to do it the long way in google docs. It seems I did this before, but I just can't find it.

Example 55.4: Displaying Plots for Simple Linear Regression This example introduces the basic PROC REG graphics syntax used to produce a standard plot of data from the aerobic fitness data set ...