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ADR-001: Content License — CC BY 4.0

Status

Accepted

Context and Problem Statement

DAGpedia's core value is sharing and evolving causal DAGs across the research community. The content (DAG files, annotations, evidence grades) needs a license that encourages reuse, adaptation, and redistribution while maintaining attribution to contributors. At the same time, many source DAGs are derived from paywalled papers, raising copyright concerns.

Considered Options

  • CC BY 4.0 — Attribution required; sharing, adaptation, and commercial use permitted
  • CC BY-SA 4.0 — Attribution + share-alike; derivatives must use the same license
  • CC BY-NC 4.0 — Attribution + non-commercial only
  • CC0 — Public domain dedication; no attribution required

Decision Outcome

Chosen option: CC BY 4.0

CC BY 4.0 best reflects the philosophy of the living DAGs framework: make knowledge freely available, reusable, and adaptable, while ensuring contributors receive credit for their work.

Consequences

  • Good: Maximum reuse — any researcher, tool, or platform can incorporate DAGpedia content with attribution
  • Good: Consistent with academic norms around citation and credit
  • Good: Compatible with downstream integration (e.g., epi-atlas)
  • Bad: CC BY-SA would have ensured derivative databases remain open, but the share-alike clause would create barriers for researchers publishing in traditional journals

CC BY 4.0 covers DAGpedia's original contributions — the dagitty encoding, evidence grades, and annotations. It does not alter the copyright status of source papers. The protection against copyright claims from paywalled papers rests on the idea-expression dichotomy: causal structures (nodes and edges as scientific knowledge) are not copyrightable. CONTRIBUTING.md requires contributors to confirm they are encoding causal knowledge fresh in dagitty format, not reproducing copyrighted figures.

References

  • https://creativecommons.org/licenses/by/4.0/
  • Reynolds RJ. Am J Epidemiol. 2026;195(5):1365–1367. https://doi.org/10.1093/aje/kwag029