Does the impact of pupil absences on achievement depend on their timing?

Using linked data from the Millennium Cohort Study and National Pupil Database (N = 8,139), this study examined how the timing of school absences (Years 1 to 11 between 2006 and 2017) affects achievement at the end of compulsory schooling in England and Wales. Absences during any school year are harmful to student achievement. However, absences in Year 1, and Years 6 (final year of primary school) to 10 (penultimate year of compulsory secondary schooling) are more detrimental to academic performance than in other years. Authorized absences hurt academic performance as much as unauthorized absences. To test the replicability and robustness of our findings, we used comparable data and analytic methods for Wales and reached the same conclusions.