Achievement is measured by utilizing similar metrics you use for any other marketing activity: leads, traffic, and customers. Counting the number of fans or followers you have can help you understand your social networking reach.
Consider a few suggestions of behaviors to measure your SMM achievement, depending upon a few common social media goals. Use metrics like volume, reach, exposure, and amplification if you want to measure awareness. If your motive is to drive more traffic to your website, then track URL shares, clicks, as well as conversions.
But the bottom line that decides its prosperity is what number of people it drives to your website, how many of them are qualified to lead, and what number of them really progress towards becoming your customers.