Network Flow for Collaborative Ranking

In query based Web search, a significant percentage of user queries are underspecified, most likely by naive users. Collaborative ranking helps the naive user by exploiting the collective expertise. We present a novel algorithmic model inspired by the network flow theory, which constructs a search network based on search engine logs to describe the relationship between the relevant entities in search: queries, documents, and users. This formal model permits the theoretical investigation of the nature of collaborative ranking in more concrete terms, and the learning of the dependence relations among the different entities. FlowRank, an algorithm derived from this model through an analysis of empirical usage patterns, is implemented and evaluated. We empirically show its potential in experiments involving real-world user relevance ratings and a random sample of 1,334 documents and 100 queries from a popular document search engine. Definite improvements over two baseline ranking algorithms for approximately 47 % of the queries are reported

An extension to the internal/external frame of reference model to two verbal and numerical domains

Moeller J, Streblow L, Pohlmann B, Koeller O. An extension to the internal/external frame of reference model to two verbal and numerical domains. EUROPEAN JOURNAL OF PSYCHOLOGY OF EDUCATION. 2006;21(4):467-487.Beside interindividual social comparisons, intraindividual dimensional comparisons in which students compare their achievements in one subject with their achievements in other subjects have an impact on their academic self-concepts. The internal/external frame of reference (I/E) model by Marsh (1986) assumes that dimensional comparisons lead to negative paths from achievement in one subject (e.g., math) to self-concept in another subject (e.g., English). In the present study, the I/E model was extended to two verbal domains (German as the native language and English as a foreign language) and two numerical domains (mathematics and physics). Grades and domain-specific academic self-concepts of N= 1440 students from 63 classes were assessed In support of the extended I/E model, (a) math, physics, German, and English achievement were positively correlated, as were; (b) se flconcepts within the verbal and numerical domains, while; (c) self-concepts between the verbal and the numerical domains were almost uncorrelated; (d) positive paths were received from math, physics, German, and English achievement on the corresponding self-concepts; (e) negative paths were found from achievement in one domain to self-concept in the other; (f) positive paths were found from math (physics) achievement to physics (math) self-concept. Finally, (g), almost no effects were found within the verbal domain, i.e., from English (German) achievement to German (English) self-concept. Therefore, there is some support for the I/E model between domains; whereas effects from achievements on self-concepts within the domains were not negative