TrustRank

TrustRank is a link analysis technique described in a paper by Stanford University and Yahoo! researchers for semi-automatically separating useful webpages from spam.

Many Web spam pages are created only with the intention of misleading search engines. These pages, chiefly created for commercial reasons, use various techniques to achieve higher-than-deserved rankings on the search engines' result pages. While human experts can easily identify spam, it is too expensive to manually evaluate a large number of pages.

One popular method for improving rankings is to increase artificially the perceived importance of a document through complex linking schemes. Google's PageRank and similar methods for determining the relative importance of Web documents have been subjected to manipulation.

TrustRank method calls for selecting a small set of seed pages to be evaluated by an expert. Once the reputable seed pages are manually identified, a crawl extending outward from the seed set seeks out similarly reliable and trustworthy pages. TrustRank's reliability diminishes as documents become further removed from the seed set.

The researchers who proposed the TrustRank methodology have continued to refine their work by evaluating related topics, such as measuring spam mass.

The TrustRank algorithm is a procedure to rate the quality of websites. It was published by Gyongyi, Garcia-Molina and Pedersen 2004. The basic idea is similar to the PageRank algorithm - taking the linking structure to generate a measure for the quality of a page. The algorithm can be seen as a further development of the PageRank procedure. However, further development is not necessarily an improvement.

The starting point of the algorithm is the selection of good (trusted) pages by hand. These pages are the sources of trust. Trust can be transferred to other page by linking to them. Trust is propagating in the same was as PageRank. Additionally one can select sources of spam. The negative measure (inverse PageRank) is propagating backwards and is a measure for bad pages (spam). For the ranking algorithm both measures can be taken into account.

Search engine optimisation for TrustRank is the same as for PageRank. Additionally, one just has to ensure the pages are not considered as spam. Suchmaschinen- Doktor