Helpful for suggesting 5 measures that can be used to weight the impact of a post:

• recursive - citerank
• use counts
• rating scores
• co-citation & hub-authority scores
• author self citations

While clearly aimed at journal article citation impact rankings, some of this could be useful to determine an impact factor for the tagging system.

In PennTags, I'd like to rate posts on their impact, and extend ratings to authors too. This could build into a matrix that supports 'tribal elders' in a community of learners. I would expect that faculty would be rated high in impact, since many students would copy or follow their posts. As their postings became more impactful, the faculty authors themselves would become more impactful too. But it is a democracy of postings, and students or staff could rise. Some, some kind of hubbing would need to be developed too.

Wow, all I can say is this is very complicated...