Ambiguity in European seasonal comparative research: how decisions on modelling shape results on inequality in learning?

Summer break study designs are used in educational research to disentangle school from non-school contributions to social performance gaps. The summer breaks provide a natural experimental setting that allows for the measurement of learning progress when school is not in session, which can help to capture the unfolding of social disparities in learning that are the result of non-school influences. Seasonal comparative research has a longer tradition in the U.S. than in Europe, where it is only at its beginning. As such, summer setback studies in Europe lack a common methodological framework, impairing the possibility to draw lines across studies because they differ in their inherent focus on social inequality in learning progress. This paper calls for greater consideration of the parameterization of “unconditional” or “conditional” learning progress in European seasonal comparative research. Different approaches to the modelling of learning progress answer different research questions. Based on real data and constructed examples, this paper outlines in an intuitive fashion the different dynamics in inequality that may be simultaneously present in the survey data and distinctly revealed depending on whether one or the other modeling strategy of learning progress is chosen. An awareness of the parameterization of learning progress is crucial for an accurate interpretation of the findings and their international comparison.