Data Mining Mehmed Kantardzic (good english books to read .txt) 📖

Borrowing from marketing theory, we measure the efficiency of a Web page by its contribution to the success of the site. For an online shop, it is the ratio of visitors that purchased a product after visiting this page to the total number of visitors that accessed the page. For a promotional site, the efficiency of the page can be measured as the ratio of visitors that clicked on an advertisement after visiting the page. The pages with low efficiency should be redesigned to better serve the purposes of the site. Navigation-pattern discovery should help in restructuring a site by inserting links and redesigning pages, and ultimately accommodating user needs and expectations.

To deal with problems of Web-page quality, Web-site structure, and their use, two families of Web tools emerge. The first includes tools that accompany the users in their navigation, learn from their behavior, make suggestions as they browse, and, occasionally, customize the user profile. These tools are usually connected to or built into parts of different search engines. The second family of tools analyzes the activities of users offline. Their goal is to provide insights into the semantics of a Web site’s structure by discovering how this structure is actually utilized. In other words, knowledge of the navigational behavior of users is used to predict future trends. New data-mining techniques are behind these tools, where Web-log files are analyzed and information is uncovered. In the next four sections, we will illustrate Web mining with four techniques that are representative of a large spectrum of Web-mining methodologies developed recently.

11.2 WEB CONTENT, STRUCTURE, AND USAGE MINING

One possible categorization of Web mining is based on which part of the Web one mines. There are three main areas of Web mining: Web-content mining, Web-structure mining, and Web-usage mining. Each area is classified by the type of data used in the mining process. Web-content mining uses Web-page content as the data source for the mining process. This could include text, images, videos, or any other type of content on Web pages. Web-structure mining focuses on the link structure of Web pages. Web-usage mining does not use data from the Web itself but takes as input data recorded from the interaction of users using the Internet.

The most common use of Web-content mining is in the process of searching. There are many different solutions that take as input Web-page text or images with the intent of helping users find information that is of interest to them. For example, crawlers are currently used by search engines to extract Web content into the indices that allow immediate feedback from searches. The same crawlers can be altered in such a way that rather than seeking to download all reachable content on the Internet, they can be focused on a particular topic or area of interest.

To create a focused crawler, a classifier is usually trained on a number of documents selected by the user to inform the crawler as to the type of content to search for. The crawler will then identify pages of interest as it finds them and follow any links on that page. If those links lead to pages that are classified as not being of interest to the user, then the links on that page will not be used further by the crawler.

Web-content mining can also be seen directly in the search process. All major search engines currently use a list-like structure to display search results. The list is ordered by a ranking algorithm behind the scenes. An alternative view of search results that has been attempted is to provide the users with clusters of Web pages as results rather than individual Web pages. Often a hierarchical clustering that will give multiple topic levels is performed.

As an example consider the Web site Clusty.com, which provides a clustered view of search results. If one keyword were to enter [jaguar] as a search onto this Web site, one sees both a listing of topics and a list of search results side-by-side, as shown in Figure 11.1. This specific query is ambiguous, and the topics returned show that ambiguity. Some of the topics returned include: cars, Onca, Panthery (animal kingdom), and Jacksonville (American football team). Each of these topics can be expanded to show all of the documents returned for this query in a given topic.

Figure 11.1. Example query from Clusty.com.

Web-structure mining considers the relationships between Web pages. Most Web pages include one or more hyperlinks. These hyperlinks are assumed in structure mining to provide an endorsement by the linking page of the page linked. This assumption underlies PageRank and HITS, which will be explained later in this section.

Web-structure mining is mainly used in the information retrieval (IR) process. PageRank may have directly contributed to the early success of Google. Certainly the analysis of the structure of the Internet and the interlinking of pages currently contributes to the ranking of documents in most major search engines.

Web-structure mining is also used to aid in Web-content mining processes. Often, classification tasks will consider features from the content of the Web page and may consider the structure of the Web pages. One of the more common features in Web-mining tasks taken from structure mining is the use of anchor text. Anchor text refers to the text displayed to users on an HTML hyperlink. Oftentimes the anchor text provides summary keywords not found on the original Web page. The anchor text is often as brief as search-engine queries. Additionally, if links are endorsements of Web pages, then the anchor text offers keyword-specific endorsements.

Web-usage mining refers to the mining of information about the interaction of users with Web sites. This information may come from server logs, logs recorded by the client’s browser, registration form information, and so on. Many usage questions exist, such as the following: How does the link structure of the Web site differ from how users may prefer to traverse the page? Where are the inefficiencies in the e-commerce process of a Web site? What segments exist