Abstract

One principal way that results of international large-scale survey assessments (ILSAs) can be of value to policy makers and researchers is in providing information on changes over time in the levels of the academic or workforce skills and competencies that ILSAs are designed to measure. Attention can be focused on these trends within each participating country, rates and direction of change can be compared across countries, and the presence of statistical relationships among trend outcomes and a variety of input and policy variables can be investigated. However, for ILSAs to be used for such purposes, the instrumentation, administration, and analysis of these assessments must be carefully controlled to ensure the results produced by a sequence of assessments can be reported on a scale that maintains a stable, comparable meaning over time. We use the term linking scales to refer to the process of accomplishing this task.