When you search, what results should be retrieved from the index and placed at the top of the search results page? In other words, what are the news, stories and videos with the most social relevance right now? Firstly, being a realtime search engine, OneRiot ranks its results at search-time. That’s key. Realtime search results need to be ordered based on social relevance right now, not sometime recently.

Secondly, we have invented a new ranking algorithm – PulseRank – to drive the realtime ordering of our search results. Think of PulseRank as PageRank for the realtime time web. If PageRank reflects historical dependability, then PulseRank reflects current social buzz. PulseRank is the ranking algorithm for the 40% of searches that traditional search engines struggle with.

Our PulseRank algorithm actually looks at dozens of factors that give “weight” to certain results in realtime. As a previous blog post noted in detail, these include:

Freshness: A story published 2 minutes ago is probably more interesting than one published 2 weeks ago, if the user is performing a browse search. But the ranking algorithm also accounts for the fact that the most recently published content is not necessarily the most relevant. The realtime stream – aka the firehose – can be noisy and filled with spam.

Domain Authority: Just because I’ve published a post on my own personal blog about Obama, should that be weighted more highly than a post from, say, the New York Times, on the same subject published at the same time? PulseRank considers factors like the number links being shared from a particular domain right now, and increases the weight for links from currently popular domains.

People Authority: PulseRank considers who shared the link on the social web. Known spammers tend to pummel their social graph with the same link many times a day. Links shared in this manner will get a lower weight in our system. More thoughtful social web users share links that tend to get retweeted and heavily dugg. Those links get a higher weight.

Acceleration: PulseRank considers whether a link is increasing in hotness or decreasing in hotness. For example, we assess whether more people are sharing the link right now than they were 2 minutes ago. The algorithm is weighted to favor “emerging” webpages rather than popular ones that everyone already knows about.

These are just four of dozens of factors that combine, at search-time, to calculate a page’s PulseRank, which determines where the link sits on our search results page. The end result to you, the user, should be better results. In short, the most socially relevant content on the web, related to your search query, should be the top result.