Presencia y visibilidad web de las universidades públicas espa olas

The evolution of size and visibility of the Spanish public universities websites according to various search engines (Google, Yahoo!, Live/Bing y Exalead) was studied from January to June 2009. Additionally, the article proposes two indicators for understanding the importance of a web domain: the Relative representativeness size factor (Rs) and the Relative representativeness visibility factor (Rv). These indicators, which consider the number of both documents and links, respectively, during a specific interval of time are intended to be applied in the design and construction of university rankings based on cybermetric techniques. The results confirm that the size differences among academic web domains vary significantly depending on the search engine used; therefore the use of a single web browser cannot supply reliable information about the actual size of the web domain. Moreover, the use of combined values from the mean obtained from each search engine does not offer reliable results, given the variance of data obtained from the different search engines, as well as the index differences of Rs. The differences concerning visibility were smaller, but significant nonetheless. Rs and Rv indicators were found to provide useful and consistent information about the level of development of universities on the Web during a given time interval. There was also a positive correlation between these two indicators on both Yahoo! and Exalead, confirming the relationship between the number of documents of an academic web domain and the number of links it receives over time. Se estudia la evolución del tama o y visibilidad de los dominios web de las universidades públicas espa olas desde enero hasta junio de 2009 en función de diversos buscadores web (Google, Yahoo!, Live/Bing y Exalead). Asimismo, se proponen el factor de representatividad relativa media en tama o (Rs) y el factor de representatividad relativa media en visibilidad (Rv) como indicadores para conocer la importancia de un dominio, en número de documentos y de enlaces externos respectivamente, durante un intervalo temporal, con el propósito de ser aplicados en el dise o y construcción de rankings de universidades basados en técnicas cibermétricas. Los resultados confirman que las diferencias de tama o entre los dominios académicos web son muy grandes según el buscador utilizado, por lo que el uso de un único buscador no permite conocer de forma fiable el tama o real de un dominio web. Además, el empleo de valores combinados a partir de la media obtenida en cada buscador no ofrece resultados fiables, dad