Studies in Informatics and Control, Vol. 19, No. 2, June 2010 169 1. Introduction Access to information is an increasingly frequent topic discussed both at national and international level. Today we can not talk about some traditional information skills, where each country can have access to virtual planetary database. The main reason why people require information on another medium than the traditional one concerns the need of some specialised information. For example, in the field of science, it takes a long time to update information. Some specialized, cutting-edge information can be found only on this media, because the lengthy book publication process required for a traditional format makes printed books obsolete. Development of online services must be the main concern in librarian world. In "WWW Library Directory" magazine [15] are identified over 30 types of services involving using of internet and reference services, databases and indexes sites, search guides, information services for trade and industry, banks of images, and so. In December, 1999 the European Commission launched an initiative entitled "eEurope: An Information Society for All", [16] initiative which proposed ambitious targets, namely to provide the benefits of information society to all Europeans. The initiative focuses on ten areas of priority, from education to transportation, from health to disability issues. The idea behind this initiative was to build a strategy to modernize the European economy, hoping that it will become "the most competitive and dynamic knowledge-based economy in the world" [4]. In the same idea was started also a project for Romania [1]. Recently there was a new generation of Web technologies designed under the concept of Semantic Web project launched by Tim Berners-Lee [2]. The semantic Web seeks to access the data with heterogeneous semantics and obtain some useful knowledge from data through various services offered in the Web space. Semantic Web claims to improve communication between peoples using different technologies, extending the interoperability of databases and providing new mechanisms for agent-based data computation in which the people and the machines will work online and make possible a new level of interaction between scientific communities [5] [12]. 2. Analyzing Text Data and Information Retrieval Information retrieval (IR) is a field developed in parallel with database systems. Information retrieval is concerned with the organization and retrieval of information from a large number of text-based documents. A typical information retrieval problem is to locate relevant documents based on user input, such as keywords or example documents. Usually information retrieval systems include on-line library catalogue systems and on-line document management systems. Since information retrieval and database systems each handle different kinds of data, there are some Statistical Methods for Performance Evaluation of WEB Document Classification Daniel Volovici 1 , Macarie Breazu 2 , Gabriel Dacian Curea 3 , Daniel Ionel Morariu 4 “Lucina Blaga” University of Sibiu, 10, Victoriei Blv., 550024, Sibiu, Romania 1 daniel.volovici@ulbsibiu.ro; 2 macarie.breazu@ulbsibiu.ro; 3 adi.mitea@ulbsibiu.ro; 4 daniel.morariu@ulbsibiu.ro Abstract: The principal aim of this paper is to make a review of main statistical methods for classifying documents that could be easily adapted in the context of Web document retrieval. After presenting the most popular methods of classification we will also define the most accurate indicators for assessment of classifiers performance. Thus we will refer to the recall, precision, fscore, sensitivity and specificity. We will also describe how these indicators can be calculated in the context of Web documents. Keywords: Information retrieval, Classification, Naïve Bayes, Evaluation metrics.