What is SiteRank?
If PageRank measures the importance of an individual page, SiteRank measures the quality of a site. Major factors that can measure the quality of a site may include:
- strength of content (size of the related content pages),
- quality of links (links from diversified sites with variant anchor text to many different pages),
- freshness of the content (regular update of content),
- uniqueness of content (less percentage of duplicate content),
- age of the site,
- outgoing links (less percentage of deadlinks and more relevant links), and
- Pagerank.
It's not harder to come up with a simple mathematical formula for calculating the SiteRank.
Why SiteRank and How Does It work?
When Sergy Brin and Larry Page (Google founders) weren't happy about the search results from early search engines (lycos, excite etc.), they tried Latent Semantic Indexing (LSI) to improve the quality of search results. SLI didn't work really well. One of things they noticed that was some one-sentence page ranked #1 for very competitive search terms. So they introduced PageRank from Graphic Theory. PageRank drastically improved the quality of search results and the performance of search. A search engine can serve majority of searches using a small amount of documents. It (may) work like this:
- if the search terms aren't specific, look at pages with higher PR pages (PR4 or higher?) only
- if it can't find enough matching pages, search for pages with lower PRs.
- if the search terms are very specific, search for both higher and lower PR pages.
That was when Google had a few million pages in its index database. Now with billions of pages in the index database, the new heuristic algorithm may work like this:
- if the search terms aren't specific, look at pages from sites with higher SiteRanks (SR4 or higher?) only
- if it can't find enough matching pages, search for pages from sites with lower SiteRanks.