In addition, Factiva scans Twitter.com feeds to score individuals based on the number of times they tweet, as well as the number of times they're mentioned in tweets.

WSJ: Methodology for NYIndex

We also looked closely at prices, totaled up mentions in the print media over the past year as tracked by Factiva and took into account recent gallery exhibitions, museum shows and awards.

FORBES: Magazine Article

An algorithm then generates a Factiva influence score.

WSJ: Methodology for NYIndex