International studies of educational achievements have been conducted since the early 1960s. According to Husén and Tuijnman (1994, p. 6), such an empirical approach in comparative education was made possible by developments in sample survey methodology, group testing techniques, test development, and data analysis. A group of American and European scholars conducted a pilot study from 1959 to 1961 to examine the feasibility of using achievement tests administered to comparable samples of students in cross-national studies to measure the “yield” of educational systems. Key questions were whether it would be possible to develop an appropriate methodology for testing and for processing and analysing data in such a way that meaningful cross-national comparisons could be made. Answers from the feasibility study were sufficiently encouraging to lead to the establishment of the International Association for the Evaluation of Educational Achievement (IEA) which conducted the first large-scale international study of educational (mathematics) achievement (Husén, 1967).