Wicherts 2006 — 73% non-compliance, 141 APA psychology papers

Wicherts, Borsboom, Kats, and Molenaar requested raw data from authors of 141 psychology papers published in journals of the American Psychological Association in 2005. The authors had signed the APA's data-sharing compliance certification at submission. 73% failed to produce data on request.

The study is the earliest of the four direct-contact cohorts that constitute the C-0002 baseline. It establishes that the non-delivery pattern is not a 2020s artifact and not a biomedicine-specific phenomenon — it was already present at this magnitude two decades ago, in psychology, at journals with explicit data-sharing policies.

The 73% lower bound of the C-0002 range comes from this study. The combination of E-0001, E-0002, E-0003, E-0004 establishes the range at 73-93% across two decades, four disciplines, and four funder regimes — converging on the same finding from independent starting points.