The only social media metric that really matter.
Social media can be daunting or even complex if we see it as a whole. It can even be a mess...
One of the best ways to keep things under control would be to measure it.
as the saying goes "you can only improve what you measure", so knowing the math behind social media certainly helps.
This brings me to a whole list of tools which may or may not provide metrics for measuring social media.
Too long a list? No problem, try reading Social Media Metrics written by Jim Stern.
Still overly complex?
Try reading a research paper that is published by HP Social Computing Labs : "Predicting the Future with Social Media"
The premise is this: the rate of tweets posted about you/your product/company is the most accurate predictor of success.
Kudos to HP Social Computing Labs.