Eliminating Noisy Information in Web Pages for Data Mining



A commercial Web page typically contains many information blocks. Apart from the main content blocks, it usually has such blocks as navigation panels, copyright and privacy notices, and advertisements (for business purposes and for easy user access). We call these blocks that are not the main content blocks of the page the noisy blocks. We show that the information contained in these noisy blocks can seriously harm Web data mining. Eliminating these noises is thus of great importance. In this paper, we propose a noise elimination technique based on the following observation: In a given Web site, noisy blocks usually share some common contents and presentation styles, while the main content blocks of the pages are often diverse in their actual contents and/or presentation styles. Based on this observation, we propose a tree structure, called Style Tree, to capture the common presentation styles and the actual contents of the pages in a given Web site. By sampling the pages of the site, a Style Tree can be built for the site, which we call the Site Style Tree (SST). We then introduce an information based measure to determine which parts of the SST represent noises and which parts represent the main contents of the site. The SST is employed to detect and eliminate noises in any Web page of the site by mapping this page to the SST. The proposed technique is evaluated with two data mining tasks, Web page clustering and classification. Experimental results show that our noise elimination technique is able to improve the mining results significantly. Categories and Subject Descriptors
The rapid expansion of the Internet has made the WWW a popular place for disseminating and collecting information. Data mining on the Web thus becomes an important task for discovering useful knowledge or information from the Web [6][9]. However, useful information on the Web is often accompanied by a large amount of noise such as banner advertisements, navigation bars, copyright notices, etc. Although such information items are functionally useful for human viewers and necessary for the Web site owners, they often hamper automated information gathering and Web data mining, e.g., Web page clustering, classification, information retrieval and information extraction. Web noises can be grouped into two categories according to their granularities: Global noises: These are noises on the Web with large granularity, which are usually no smaller than individual pages. Global noises include mirror sites, legal/illegal duplicated Web pages, old versioned Web pages to be deleted, etc. Local (intra-page) noises: These are noisy regions/items within a Web page. Local noises are usually incoherent with the main contents of the Web page. Such noises include banner advertisements, navigational guides, decoration pictures, etc. In this work, we focus on detecting and eliminating local noises in Web pages to improve the performance of Web mining, e.g., Web page clustering and classification. This work is motivated by a practical application. A commercial company asked us to build a classifier for a number of products. They want to download product description and review pages from the Web and then use the classifier to classify the pages into different categories. In this paper, we will show that local noises in Web pages can seriously harm the accuracy of data mining. Thus cleaning the Web pages before mining becomes critical for improving the data mining results. We call this preprocessing step Web page cleaning.

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