Web analytics provider Webtrends, has released Hoverstats, a free tool that will essentially add a new layer of data for brands to evaluate their Facebook performance.

The core feature of Hoverstats is its Post Strength Indicator (PSI), which is a metric that assigns a score to an individual Facebook Page post based on the total reach that is achieved through fan engagement.

The Webtrends PSI uses data from Facebook’s new Page Insights API to provide scores for a brand’s individual posts. This will give brands a simple way to evaluate fan engagement through specific posts. 

Each post receives a number score from 1 to 100, based on indicators such as likes, shares, comments and reach. Scores are updated regularly, and past posts can also be rescored.

"With our new PSI score system, we're helping marketers, one post at a time, develop and publish Facebook wall content that fans truly engage with," says Alex Yoder, chief executive officer, Webtrends. "Overall, we see this as a way to help make the Facebook ecosystem a better place for both brands and users."

Currently, Hoverstats can be installed through a Google Browser plug-in by anyone who manages a Facebook Page. However, in the near-future, Hoverstats will be available on other browsers, including Internet Explorer and Firefox.