A Natural Experiment in Education Reform: The Case of Upper‐Secondary Curriculum Compression

ABSTRACT We use a change in Iceland's education system as a natural experiment to measure the effect of years spent in upper‐secondary school on subsequent first‐year outcomes at university. The duration of Iceland's upper‐secondary education was shortened by 1 year through compression of the curriculum. We find that shorter upper‐secondary education, 3 years instead of the previous four, leads to first‐year university students completing fewer credits, getting a lower average grade in completed courses, and being more likely to drop out. We find that this negative effect of the reform disproportionately affected the academic performance of male students and those who previously demonstrated weaker academic abilities, thus increasing academic disparities.