Comparability issues in international educational comparisons

The diversity of education systems and differences in the structure of the governance of education make international educational comparisons very difficult. There are various parameters that affect the comparability of international educational data and data which are adequate for certain types of comparisons may reveal to be entirely inadequate for other types of comparisons. This article attempts to identify these parameters and illustrates the impact of methods of data collection on the comparability of data. Account is thereby taken of various trade-offs between comparability, coverage, uniformity, complexity, and other attributes of educational comparisons. This article concludes that there are no absolute criteria for comparability but that for an adequate use of data the knowledge of different quality-relevant properties of the data in the form of structured meta-data is an essential requirement.