Hi guys - I'm really impressed with what you're doing with the attention score. I assume you have already looked at integrating Twitter data into the score. I can understand why you would stick with FB data to start with, but you could potentially use Twitter as a proxy score to validate against the FB attention score.
I would suggest something along the lines of:
1) pull article URLs tweeted from authorised publisher account & store URL and time of tweet
2) return to tweet URL after a set period of time (e.g. 30 / 60 mins, 4 / 8 hours) to measure increase in twitter engagement score. I would score engagement with tweets as:
number of re-tweets, likes, total number of comments. Probably in that priority order.
4) calculate the velocity increase in engagements, i.e. how quickly did the tweet gain engagements over the period of time measured, how did this number change during the next period, and so forth
This gives you a twitter engagement score for each article URL, and a velocity engagement score for each tweeted URL (which should be an indicator of how much attention that URL gained over a set period of time). It may also be a way to get you access to Twitter data via the free API rather than having to immediately go to Gnip for the firehose (which would of course be great, but probably quite expensive). You can then go on to compare this Twitter score against other tweeted articles, FB scores and front page exposure within the overall attention score.
Happy to discuss this further if it's of interest - I've spent a fair bit of time working with the twitter API on this type of scoring mechanism recently.
All the best from your former colleague,
Paul R.