The role of diversity and ensemble learning in credit card fraud detection.

The number of daily credit card transactions is inexorably growing: the e-commerce market expansion and the recent constraints for the Covid-19 pandemic have significantly increased the use of electronic payments. The ability to precisely detect fraudulent transactions is increasingly important, and machine learning models are now a key component of the detection process. Standard machine learning techniques are widely employed, but inadequate for the evolving nature of customers behavior entailing continuous changes in the underlying data distribution. his problem is often tackled by discarding past knowledge, despite its potential relevance in the case of recurrent concepts. Appropriate exploitation of historical knowledge is necessary: we propose a learning strategy that relies on diversity-based ensemble learning and allows to preserve past concepts and reuse them for a faster adaptation to changes. In our experiments, we adopt several state-of-the-art diversity measures and we perform comparisons with various other learning approaches. We assess the effectiveness of our proposed learning strategy on extracts of two real datasets from two European countries, containing more than 30 M and 50 M transactions, provided by our industrial partner, Worldline, a leading company in the field.

Sex and cultural differences in the acceptance of functional foods: a comparison of American, Canadian, and French college students.

OBJECTIVE: Functional foods (FF)--foods containing nutritional supplements in addition to natural nutrients--have an increasing presence in the marketplace. Expanding on previous research, the authors investigated college students' acceptance of FF. PARTICIPANTS: In September--March 2004, 811 undergraduates in Canada, the United States, and France participated in the study. METHODS: A self-administered questionnaire measured students' general food attitudes and beliefs as well as FF-related knowledge, attitudes, beliefs, and purchase intention. RESULTS: Overall, participants slightly favored FF over traditional foods. However, although most respondents associated FF with positive health benefits, many remained dubious of currently available FF information. In terms of culture and sex, the authors found small but significant divergences in FF knowledge, attitudes, and behaviors. CONCLUSIONS: Stronger labeling and education efforts may increase cross-cultural acceptance of FF by college students.