Research and evaluation
Lower average scores do not, by themselves, tell us why achievement has declined. This study examines comparisons across the 2018, 2022 and 2025 PISA rounds and the evidence used to explain their differences.
2018 / 2022 / 2025
The analyses draw on common test items and response times, measurement models, socioeconomic and population-composition comparisons, TIMSS pupil panels, and other international and national assessments. They examine whether proposed explanations fit the patterns across countries, subjects and groups of pupils.
The comparisons provide factual counterarguments to simple, single-factor explanations. They do not establish that any proposed factor is irrelevant or estimate how much each caused the decline. Country-level associations, descriptive adjustments and intervention studies answer different questions.
Milos Kankaras, 2026. Independent analytical brief, 15 pages and ten charts; not a peer-reviewed article or an OECD publication.
One national average covering seven separate school systems. A country note on how much of the country's largest recorded PISA gain is improved learning rather than a changed test population, and how far the measurement itself can be pushed.
Nine secondary analyses of public microdata, including the Montenegro study, published by the Center for Psychology.
Research on whether scores support comparisons across cultures and education systems.
