Administrative data is any data collected by national or local governments (i.e. ministries, agencies etc.) outside of the context of an impact evaluation. Examples include national census data, tax data, and school enrollment data. Administrative data is generally not initially collected for research purposes but rather to document or track policy beneficiaries, firm owners and the general population. Researchers should aim not to use administrative data in place of survey data but rather in addition to it.
Administrative data offers advantages in quality, cost, and time. It is often considered more accurate than self-reported survey data; consider, for example, that a firm is more likely to accurately report its turnover rate to Financial Administrations than to a research team conducting a firm survey. Furthermore, notwithstanding potential access costs, administrative data doesn't pose additional costs as it is collected independent of the impact evaluation. Finally, administrative data can avail information frequently because it is often collected on a regular basis. This makes administrative data especially advantageous and attractive for research teams retrospectively evaluating interventions for which data collection did not occur.
Nonetheless, administrative data doesn't come without a few potential challenges: access, merging, and quality. Accessing administrative data requires strong relationships with national and/or local authorities. In some cases, authorities may not be inclined to share the information. Once accessed, consolidating administrative data with other data often entails merging different databases together: this can be an extensive task when no common unique identifiers exist across the databases. Finally, while in some cases administrative data can provide high accuracy, in others, it may be badly reported, not exhaustive, or not at all existent. Not all governments have the same capacity to collect this information.