Bill Slawski who is an expert at tearing into all the patents search engines file and explaining them in layman’s terms has put together a list of twenty possible ways search engines rerank pages before they deliver them to a searcher. I’ll list the first three below but definitely check the entire article out as it is an interesting read.
1. Filtering of duplicate, or near duplicate, content
Search engines don’t want the same page or content to fill search results, and pages that are substantially similar may be filtered out of search results. While not technically a reranking of search results, as Dr. Garcia notes in Search Engine Patents On Duplicated Content and Re-Ranking Methods, this type of filtering has the result of changing the order in which results are returned to a searcher.
2. Removing multiple relevant pages from the same site
It isn’t uncommon for more than one page from a site to be relevant to a search query. Search engines try to limit the amount of pages displayed in search results from the same site. If there is more than one page from a site that ranks for a search, a search engine may show a second result from that site after the first result, indenting the second page, and inserting a link to “more results from this site.” Additional results may not be shown.
3. Based upon personal interests
A search engine may try to rerank results for a search to a specific searcher based upon past searches and other tracked activity on the web from that person. This kind of reranking may rely upon a person logging on to a personalized search. Here are a few different looks at how that might be accomplished:
- Personalizing Search via Automated Analysis of Interests and Activities (pdf)
- Variable personalization of search results in a search engine
- Personalization of web search
Bill ends his list with the following advice, “This isn’t a comprehensive listing of documents or processes that describe ways search engines may rerank pages, but it covers a lot of different possibilities. Some of these reranking processes are definitely being used now, others may be in place, some may be used in the future, and a few not used at all.”