> For the complete documentation index, see [llms.txt](https://docs.communityinclusion.org/training-and-technical-assistance-materials/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.communityinclusion.org/training-and-technical-assistance-materials/apr-data-fidelity-review/historical-data-review.md).
# Historical Data Review
Before submitting current-year APR data, a comparison should be done with at least the prior year’s data and optimally with multi-year historical data to understand how key elements are increasing, decreasing, or not changing. Each screen of the APR in NATADS provides prior-year total data for that activity to make comparison easy. It is critically important for grantees to be able to explain data volume (output level) trajectory changes. Grantees can use the [CATADA data portal](https://catada.info/at/) to create custom tables with historical data to use in this review, and NATADS may be updated to pull a limited number of key data elements from the prior-year APR to provide a benchmark in the current APR to support this kind of fidelity and accuracy review.
#### Red Flag: No awareness of or ability to explain significant data change.
Grantees should be knowledgeable of their historical data and trajectory patterns over time, especially for key output data elements. Any significant changes should be understood and explained as actual variances due to some known cause (e.g., increases created by new funding and expanded program or decreases caused by program closure) or changes that are artifacts of data system integrity issues or data collection/reporting fidelity issues. If changes are caused by the latter, there should be a clear plan developed to remediate those issues to ensure cleaner and more stable data for the future.
*Last updated January 2023*
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