The OECD's Programm for International Student Assessment (PISA) is a collaborative effort among the Member countries of the OECD to measure how well young adults, at age 15 and therefore approaching the end of compulsory schooling, are prepared to meet the challenges of today's knowledge societies. The assessment is forward looking, focusing on young people's ability to use their knowledge and skills to meet real-life challenges, rather than the extent to which they have mastered a specific school curriculum. PISA is the most comprehensive and international effort to date to assess student performance and to collect data on the student, family and institutional factors that can help to explain differences in performance.