In God we trust; all others must bring data.
The real story
Quote Investigator (2017) found no primary source connecting this saying to Deming. Mary Walton's 1986 book "The Deming Management Method" included it without attribution. The earliest known use is Edwin R. Fisher (1978), who called it an already-established cliché. The saying is likely anonymous and was retroactively associated with Deming due to thematic alignment. Human review recommended before publishing as a Deming quote.
Context
A data-driven decision-making aphorism long associated with Deming's philosophy of statistical quality control. Frequently cited as a cornerstone of evidence-based management.