Asymmetric Missing-data Problems: Overcoming the Lack of Negative Data in Preference Ranking

In certain classification problems there is a strong a asymmetry between the number of labeled examples available for each of the classes involved. In an extreme case, there may be a complete lack of labeled data for one of the classes while, at the same time, there are adequate labeled examples for the others, accompanied by a large body of unlabeled data. Since most classification algorithms require some information about all classes involved, label estimation for the un-represented class is desired. An important representative of this group of problems is that of user interest/preference modeling where there may be a large number of examples of what the user likes with essentially no counterexamples.Recently, there has been much interest in applying the EM algorithm to incomplete data problems in the area of text retrieval and categorization. We adapt this approach to the asymmetric case of modeling user interests in news articles, where only labeled positive training data are available, with access to a large corpus of unlabeled documents. User modeling is here equivalent to that of user-specific document ranking. EM is used in conjunction with the Naive Bayes model while its output is also utilized by a Support Vector Machine and Rocchio's technique.Our findings demonstrate that the EM algorithm can be quite effective in modeling the negative class under a number of different initialization schemes. Although primarily just the negative training examples are needed, a natural question is whether using all of the estimated labels (i.e., positive and negative) would be more (or less) beneficial. This is important considering that, in this context, the initialization of the negative class for EM is likely not to be very accurate. Experimental results suggest that EM output should be limited to negative label estimates only.     

International Approaches to Whole-of-School Physical Activity Promotion

Increasing physical activity opportunities in schools has emerged as a global priority among school-aged youth. As a result, many countries have designed and implemented whole-of-school physical activity initiatives that seek to increase physical activity opportunities that are available to school-aged children before, during, and after school. Considering the comprehensive school physical activity program conceptual framework, this article includes a discussion of the initiatives from four countries: Finland (Finnish Schools on the Move), Ireland (Active School Flag), Poland (PE with Class), and the United States (Let’s Move Active Schools). Background information, implementation strategies, best practices, development opportunities, and relevant research from each country will be presented. Exploring different perspectives sheds some light on the international landscape relative to whole-of-school physical activity promotion and provides direction for future and continued research and practice.     

The Joinville School and the Institutionalization of a French-Style Physical Education, 1852–1939

Since the mid-nineteenth century, the Joinville School in France has worked to promote an innovative method of physical education, the French method, which was strongly marked by ideological and geopolitical challenges. Most of the French actors, whether they be military, doctors, scientists, or teachers, fought to defend France on the move. Physical education and its scholastic responsibility thus represented an original means to serve the national community and to give the country the necessary influence it required on the political and cultural international scene. If during the Second Empire, the Joinville School participated in the development of the physical instruction of French troops, during the third Republic, this officers' training school expanded the promotion of its method for physical education in schools. Among the challenges of this strategy, the actors for French physical education were faced with the organization of a common national teaching method as additional support for the promotion of a method that bore the mark of an eclectic philosophy. Until World War II, the Joinville School was a center for innovation that would spread practical physical education throughout France and Europe.     

Educational research and Polish perestroika

Deputy to the Diet and Vice-chairman of the Diet's Commission for Education and Youth. Chairman of the Polish Pedagogical Society. Vice-chairman of the Franco-Polish parliamentary group. Author of a number of publications on youth and education.     

Relative indexing on the basis of users' profiles

Principles for determining the profile of a system user have been presented. These principles are based on the analysis of co-occurrence of index terms in queries and pertinent documents. Moreover, a procedure for determining index term weights on the basis of user profiles has been introduced. The information value of the index term weights depends on the degree of homogeneity of the system users.