A General Evaluation Framework for Topical Crawlers

Topical crawlers are becoming important tools to support applications such as specialized Web portals, online searching, and competitive intelligence. As the Web mining field matures, the disparate crawling strategies proposed in the literature will have to be evaluated and compared on common tasks through well-defined performance measures. This paper presents a general framework to evaluate topical crawlers. We identify a class of tasks that model crawling applications of different nature and difficulty. We then introduce a set of performance measures for fair comparative evaluations of crawlers along several dimensions including generalized notions of precision, recall, and efficiency that are appropriate and practical for the Web. The framework relies on independent relevance judgements compiled by human editors and available from public directories. Two sources of evidence are proposed to assess crawled pages, capturing different relevance criteria. Finally we introduce a set of topic characterizations to analyze the variability in crawling effectiveness across topics. The proposed evaluation framework synthesizes a number of methodologies in the topical crawlers literature and many lessons learned from several studies conducted by our group. The general framework is described in detail and then illustrated in practice by a case study that evaluates four public crawling algorithms. We found that the proposed framework is effective at evaluating, comparing, differentiating and interpreting the performance of the four crawlers. For example, we found the IS crawler to be most sensitive to the popularity of topics.Partially supported by National Science Foundation CAREER grant No. IIS-0133124/0348940.     

Long-term trends in home advantage in professional team sports in North America and England (1876-2003)

Home advantage is quantitatively defined and calculated for each season since the start of the main professional sports in North America and England. Over 400,000 games are analysed. The leagues represented are the National League (1876-2002) and American League (1901-2002) for baseball, the National Hockey League (1917-2003) for ice hockey, the National Football League (1933-2002) for American football, the National Basketball Association (1946-2003) for basketball, and the four levels of professional football, formerly called the Football League, in England (1888-2003). Problems caused by unbalanced playing schedules are considered. The results are presented graphically to show long-term trends and sudden changes. The highest levels of home advantage for all sports were in their early years of existence. Home advantage in ice hockey, basketball and football in England has declined over the last two decades. In baseball there has been very little change over the last 100 years, with home advantage consistently lower than in other sports. There was a large drop in home advantage in football in England following the 7-year suspension of the league during the Second World War. The trends and changes provide some evidence that travel and familiarity contribute to home advantage, but little in support of crowd effects.     

Game location and aggression in rugby league

The present study examined the relationship between aggression and game location in rugby league. We videotaped a random sample of 21 professional rugby league games played in the 2000 Super League season. Trained observers recorded the frequency of aggressive behaviours. Consistent with previous research, which used territoriality theories as a basis for prediction, we hypothesized that the home team would behave more aggressively than the away team. The results showed no significant difference in the frequency of aggressive behaviours exhibited by the home and away teams. However, the away teams engaged in substantially more aggressive behaviours in games they lost compared with games they won. No significant differences in the pattern of aggressive behaviours for home and away teams emerged as a function of game time (i.e. first or second half) or game situation (i.e. when teams were winning, losing or drawing). The findings suggest that while home and away teams do not display different levels of aggression, the cost of behaving aggressively (in terms of game outcome) may be greater for the away team.