Managing Metadata Diversity in Longitudinal Studies: Lessons from the Nacda Portal's DDI-L Implementation

The National Archive of Computerized Data on Aging (NACDA) has been preserving and sharing data on aging populations for nearly 50 years. Over the last several years, we have been using DDI-L to create longitudinal comparisons within and across data collections we host. Our repository frequently manages complex data collections, or studies, consisting of separate datasets for each wave, aggregated datasets containing multiple waves, or other assorted combinations.In this presentation we discuss our experience working with the metadata from diverse data collections for the NACDA Portal, and how variations across those studies and series raise questions about added value and the costs and benefits of this work for use in the secondary researcher community. As one of the few repositories utilizing DDI-L for multi-source metadata comparison, our experiences may help inform best practices and emerging standards in the broader research data community. We also hope to gather insights about data management processes, particularly for longitudinal research data. This PPT was presented at IASSIST virtual on June 3, 2026, Session E.3, and contains 10 slides.