Web Impact Factor
The Web Impact Factor ( WIF ) is a transfer of the bibliometric principle of the Impact Factor for specialist journals to websites or domains in the World Wide Web . It is used in webometry to assess the influence of websites. Just like the impact factor, the web impact factor is not without controversy, since only the number of links to a page is taken into account to determine it, not its content.
As early as 1997, Rodríguez i Gairín used the AltaVista search engine in a study to compare the influence of Spanish universities on the Internet. In 1998 Peter Ingwersen coined the term "Web Impact Factor" (WIF) for the coefficient used. He calculated the WIF as the number of web pages that contain at least one link to a particular website divided by the number of individual pages that make up that website.
The WIF can be used not only on individual websites, but also on entire areas of the web, such as B. the entire pages of a university or all pages of a country (or a country-specific top-level domain ). The "external web impact factor" is a variant in which the links within the examined website are excluded, so that only the links from other websites are included in the calculation. This practice is common.
Later studies show that the informative value of the WIF can be significantly increased if one does not use the number of individual documents that make up the website under investigation as the denominator, as their value depends on the design of the website (e.g. a more extensive Text can be placed in one large HTML document or in many small ones). Since the WIF is primarily calculated for research institutions, Mike Thelwall named the following calculation as a more objective alternative: The WIF is calculated from the number of incoming links (external) divided by the number of employees of the examined institution (in full-time equivalents).
Search engines are usually used to determine the number of links to a page . This can be problematic under certain circumstances, as the figures they provide are not verifiable and do not cover all websites. Most search engines, including Google, cannot determine the WIF, as the number of links to any page of a domain cannot be determined.
The number of links on a page is also part of most search engine ranking algorithms. However, Google's PageRank does not match the WIF.
calculation
The calculation of the external web impact factor is based on the formula:
example
A search at AltaVista resulted in the following data:
- Counter - number of external link pages
- Search query link: www.denic.de AND NOT (link: www.denic.de AND host: www.denic.de) returns 38,200 hits
- With this search query, the external links are determined. All internal ones are excluded by the "AND NOT" operator.
- Denominator - number of pages on the host
- Search query host: www.denic.de returns 3,560 hits
- Means "host" the number of websites is determined on a specified host.
This results in an EXT-WIF of 10.73 for http://www.denic.de(as of July 20, 2006).
literature
- Peter Ingwersen : The calculation of Web Impact Factors . In: Journal of Documentation, Issue 54, Number 2, 1998, pp. 236–243.
- Alireza Noruzi: The Web Impact Factor: A Critical Review . In: The Electronic Library, Issue 24, Number 4. [1]
- Mike Thelwall : Extracting macroscopic information from web links . In: Journal of the American Society for Information Science and Technology 52 (13), 1157-1168.
- JM Rodríguez i Gairín: Valorando el impacto de la information en Internet: AltaVista, el "Citation Index" de la red . In: Revista Española De Documentación Científica, Edition 20, Number 2, 1997, pp. 175–181. [2]
Individual evidence
- ^ Peter Ingwersen: The calculation of the web impact factors. In: Journal of Documentation, 54 (2), 1998, pp. 236-243.