Measurement: Creating A Social Media Impact Factor

There is a metric used for scholarly journals called the impact factor (IF).  In the world of medical and professional journals, the criteria for influence is citations.  Similar to how much of the social media world uses inbound links - the citation metric carries significant weight in scientific and academic communities.  It also raises significant debate from critics who feel it is an incomplete measure.  A few shortcomings of the impact factor include:

• Ability for original authors of an article to affect the IF by citing their own publication in other articles
• Too short a time window for citations, ignoring ongoing citations to older "classic" articles
• Only counting the frequency of citations and disregarding the prestige of the citing journals
• IF is only relevant for certain fields like science or economics, but not for other fields like literature or less citation based

BUT it is the best that the scientific community has and it is used extensively.  Does any of this sound familiar?  Many of these are the same issues that bloggers are raising with services like Technorati and sparking discussion about what influence and authority really means in social media.  I like the word "impact" because it seems concrete.  Impact seems measurable.  But what is the model that should emerge for how to measure it in relation to words already in use like authority or influence?  I think part of the difficulty in finding the right model comes from not really understanding the right elements to measure.  Right now, the most popular metric for bloggers is Authority from Technorati, and this is based mostly on volume.  Most people agree we need more sophistication, but rather than massaging existing models ... we need to have a common understanding of what the most important criteria are to measure to really understand the impact factor of a particular blog. 

To that end, here are the five areas of measure I think we should be focusing on:

• Volume - how many unique mentions did it get?
• Prestige - how influential were each of the mentions?
• Depth - how detailed were each of the mentions? 
• Time - over what period of time did the mentions happen?
• Reputation - how well regarded or well known is the author in their area?

What do you think about these?  If there were a measurement model that could account for each of these criteria, would it paint a complete picture of influence and allow comparison between blogs?  More importantly, has anyone already sorted this out and managed to built a model to go beyond volume and encompass some of the other areas?