How to Measure Social Media Success

If a marketing campaign is to be successful, and repeated, it must be measured. How would you know if it was a success, or be worth repeating otherwise?

The fist step should be to ask "why"? The same question applies to any marketing campaign, be it search marketing, radio, television, or anything else. Why does this website exist? Why am I doing this and what result am I trying to achieve?

More...