Abstract

Administrative data are increasingly reused for planning, performance monitoring, and accountability across public institutions. While this expansion enhances data availability, it also introduces challenges for statistical interoperability, particularly when indicators rely on inconsistent or weakly specified denominators. Such inconsistencies may remain hidden when indicators are reported repeatedly over time, creating an appearance of stability that masks underlying measurement misalignment.
This study examines denominator choice as a critical but often under-recognised dimension of statistical interoperability. Using publicly available tertiary education participation indicators from the UNESCO Institute for Statistics, it contrasts two conceptually related measures, the gross enrolment ratio and the net enrolment rate, to demonstrate how indicators intended to capture the same phenomenon can yield substantially different interpretations solely due to the denominator definition. Simple descriptive comparisons for the latest available reporting year illustrate how apparent differences in performance can arise from calculation choices rather than real-world change.
The study further considers the implications of revising long-standing indicators once denominator misspecification is identified. While methodological correction improves measurement validity, it can introduce breaks in series, complicating longitudinal interpretation and accountability reporting. This highlights the importance of metadata discipline, transparency, and governance mechanisms in managing indicator evolution over time. By framing interoperability as a statistical design and measurement issue rather than a technical integration problem, this contribution highlights the role of coherent metadata in ensuring comparability, trust, and effective reuse of administrative and official statistics.