PostRank™
PostRank is a scoring system developed by AideRSS to rank any kind of online content, such as RSS feed items, blog posts, articles, or news stories. PostRank is based on social engagement, which refers to how interesting or relevant people have found an item or category to be. Examples of engagement include writing a blog post in response to someone else, bookmarking an article, leaving a comment on a blog, or clicking a link to read a news item.

PostRank measures engagement by analyzing the types and frequency of an audience's interaction with online content. An item's PostRank score represents how interesting and relevant people have found it to be. The more interesting or relevant an item is, the more work they will do to share or respond to that item so interactions that require more effort are weighted higher.
PostRank scoring is based on analysis of the "5 Cs" of engagement: creating, critiquing, chatting, collecting, and clicking. By collecting interaction metrics in these categories the overall engagement score is calculated and the PostRank value is determined.
The 5 Cs of Engagement
Creating
The strongest form of engagement is demonstrated by using an item as inspiration to create your own, for example, writing your own blog post that responds to or refutes someone else's blog post. Creation requires the most thought and investment of time, actively generates conversation, and therefore indicates the highest level of engagement.
Critiquing
Reading a blog post and then leaving a comment requires an investment of time, thought and effort (or sometimes just typing and name-calling...), and is a form of conversation. However, it requires less effort than writing a whole blog post. So while it is an important action, it does not indicate as much engagement as Creating.
Chatting
Sharing and discussing information can often be started with one click, so it doesn't require a major investment of effort. However, a desire to share is a strong indication of relevance, and the act of sharing and its ensuing discussion are acts of conversation. Use of social media applications like Twitter and Pownce encourage both the sharing of information and the resulting conversations. As a result, social media "chatting" indicates a good level of engagement.
Collecting
Bookmarking or submitting items to social sites also tend to be "one-click" actions. They are intentional acts of archiving and sharing, but don't require much time or effort. However, the sharing that occurs often sparks conversations, so Collecting does demonstrate some engagement.
Clicking
Activities like clicks and page views indicate lower engagement because they're passive interactions. Clicking a link to read a blog post doesn't require much work, and you're not giving anything back except your reading time. It is an intentional act, however, and thus indicates a mild level of interest and engagement. Which may grow after the item is read.
Engagement sources we track
Engagement sources evolve as new and interesting ways of interacting with with online content evolves. Here are several examples of engagement data sources that are included in PostRank:
Views - Pageviews within RSS readers and via PostRank widgets
Clicks - Clicks within RSS readers and via PostRank widgets
Comments - The number of comments on the item
del.icio.us - The number of bookmarks saved
Ma.gnolia - The number of bookmarks saved
Digg - The number of diggs on the item
Twitter - The number of tweets mentioning the item
Pownce - The number of times the item has been shared
Google Trackbacks - The number of links to the item on other websites
PostRank™ in Action
The PostRank data service can be used in many different ways. One example is filtering existing feeds to reduce the quantity of items a feed reader is presented. PostRank helps you engage with information that interests you. Read what matters and learn as much or as little as you want about topics, from every little bit to just the hottest news.
Let's use photography as an example topic. There are thousands of articles and blog posts about photography. Subscribers with different interest levels will have more or less time to dedicate to following news. AideRSS has built a feed management application that uses PostRank to find the articles and posts that people are talking about, helping you engage with key topics more quickly and saving you time.

Feed-based PostRank™ versus Thematic PostRank™
Feed-based PostRank helps you understand an individual feed. It allows you to filter and rank news items, against their own historical levels of social engagement. This means that a 10 for one source will represent a different level of engagement than a 10 from another source. Thematic PostRank provides further customization of the RSS user experience, enabling comparative ranking of online content from different feed sources based on user input. PostRank calculations are not normalized against a feed history but are compared to each other. This allows for ranking of news items from different sources within a topic area or channel.