An effective social media metric requires an 'auditable narrative.' The two extremes are

"Analysis paralyses" <--------------------------> "Abilene paradox"

http://en.wikipedia.org/wiki/Analysis_paralysis

http://en.wikipedia.org/wiki/Abilene_paradox

Furthermore, pluralistic ignorance, rife in the social media metrics craze, leads to dysfunction and failure of social media strategies for business. 

http://en.wikipedia.org/wiki/Pluralistic_ignorance

To often pluralistic ignorance is caused by the structure of the underlying social network.

An auditable narrative could be a simple supporting network map, some finer-grain measures accompanied by a brief prose explanation. The goal is to provide some trail of how the conclusion was reached. It is not a separate analytic product. Invariably, the narrative is far more valuable to decision making, excellence and prosperity through social media than eye watering metrics and overbearing metricians.  

For example, when the accountant says you have this much money $, and you thought you had $$$, then you want a little narrative trail to understand what happened to $$. Bank statements are important, like metrics, but it is really the narrative explanation that aids understanding. 

Narratives, per se, are perspicacious. The best offer keen mental perception, understanding and foresight. Metrics offer some fractional, logical indicators and hindsight that may inform the narrative. That’s all. To often, people may ask, 'How did you get that number?' That’s fine and necessary for the audit analyst, but not a responsible business leadership behavior. 

Narratives are simple and direct. Direction and leadership inhabits responsible narratives not metrics.

Social media are complex adaptive systems. They are propelled by self-organizing interactions and emerging collective intelligence… not metrics.