Dawid & Skene (1979) credit Dempster, Laird & Rubin (1977) as the source of the EM numerical method their model is built on

dawid-skeneEM-algorithmcrowdsourcingmachine-learning-theorymedical-statisticscitation-lineage

Dawid & Skene (1979) does not present its Expectation-Maximization approach as original numerical machinery. The paper states explicitly that "Dempster et al. (1977) describe a numerical method of maximum likelihood estimation which is ideally suited to this particular problem" — crediting Dempster, Laird & Rubin's 1977 EM algorithm paper, "Maximum likelihood from incomplete data via the EM algorithm" (J. R. Statist. Soc. B, 39, 1-38), as the source of the estimation procedure Dawid & Skene apply to their own observer-error-rate problem.

This extends the vault's existing citation lineage one hop further back. Li & Yu (2014) already credit Dawid & Skene (1979) as crowdsourcing weighted-majority voting's ancestor, and RA-RAG (2025) extends Li & Yu — the chain already traced from clinical medicine to LLM retrieval. Dempster, Laird & Rubin (1977) sits one link further back still: not a voting or crowdsourcing paper at all, but the general statistical-computation paper that supplied the numerical method Dawid & Skene needed to fit their own model. The full traced lineage is now Dempster-Laird-Rubin (1977) → Dawid-Skene (1979) → Li & Yu (2014) → RA-RAG (2025), four papers and 46 years, each link a named citation rather than a shared vocabulary.