We found this really cool article by
6 Steps to Measure Social Media ROI
How do you measure social media return on investment (ROI)?
It’s the age-old question. For many social media marketers, brands and entrepreneurs, calculating exactly what they’re getting back out of their (often very intensive) social media campaigns has proven to be a particularly difficult nut to crack. The secret, however, lies in testing.
First, set your conversion goals – this will be unique to your business but in most cases it will be a measurable action that ultimately results in an end purchase. Now, track those conversions, looking at reach, traffic, leads, customers and conversion rate.
Assign a monetary value to each conversion, and be sure to measure total benefits by channel. Determine your total costs, and then analyse all results looking to make improvements.
Check the visual below for a lot more detail, which comes courtesy of Quick Sprout.