The Engagement Score rates the level of engagement of the audience segment on the analyzed website that is being sent by a specific referral.
The score is created by comparing each respective engagement metric of traffic sent to (e.g.) amazon.com (the analyzed site) from buzzfeed.com (the referral site) to the traffic engagement metrics (bounce rate, visits, page views, etc) of top sites from the retail & apparel category (or the category of the analyzed site) that are being sent from referrals.
The formula for the affiliate engagement metric weighs bounce rate more heavily as our research shows us that it is a universal metric every site is trying to optimize.
The engagement score offers the ability to understand which affiliate is sending the most engaged traffic to the competitor (in single view) and which of the competitors has the highest engagement score (in compare view).
This also provides an additional qualification metric for users to understand which referral sites are performing best for their competitors. It can also help affiliate managers identify opportunities for better engagement (perhaps your competitor is offering a better deal through this affiliate).
For more information, see Incoming Traffic Insights.