Applied researchers in education have only recently begun to appreciate the value of international assessments, even though there is now fifty years of experience with these. This slow start may reflect both a broadening of the set of countries that participate and the move to more regular cycles of the tests. In any event, there has been a surge in analyses that focus on international comparative studies.
Until recently, these assessments have been stand-alone surveys that have not been linked, and analysis has largely focused on cross-sectional uses of the international data. While there has been no move toward following individuals over time in the main surveys, both the IEA and the OECD have recently began equating scores across assessment. This linking of examinations permits some longitudinal analysis of country changes, albeit on fairly short time dimensions.
Striethold and Rosén consider a different approach whereby they can splice together reading assessments over a much longer period. They essentially attempt to mimic psychometric linking using a subset of items for each of the IEA reading tests since 1970. The purpose is to provide data on longer term trends that permit consideration of how educational policy affects student outcomes over extended periods of time.