Controversy over statistics for mental illness among Northern blacks
The 1840 Census was the first that attempted to count Americans who were "insane" or "idiotic". Published results of the census indicated that alarming numbers of black persons living in non-slaveholding States were mentally ill, in striking contrast to the corresponding figures for slaveholding States.
Pro-slavery advocates trumpeted the results as evidence of the beneficial effects of slavery, and the probable consequences of emancipation. Anti-slavery advocates contended, on the contrary, that the published returns were riddled with errors, as detailed in an 1844 report by Edward Jarvis of Massachusetts in the American Journal of the Medical Sciences, later published separately as a pamphlet, and in a memorial from the American Statistical Association to Congress, praying that measures be taken to correct the errors.
The memorial was submitted to the House of Representatives by John Quincy Adams, who contended that it demonstrated "a multitude of gross and important errors" in the published returns. In response to the House's request for an inquiry, Secretary of State John C. Calhoun reported that a careful examination of the statistics by the supervisor of the census had fully sustained their correctness. The returns were not revised.
^John Caldwell Calhoun; South Carolina General Assembly (1859). Richard K. Crallé, ed. The Works of John C. Calhoun: Reports and Public LettersV. New York: D. Appleton and Company. p. 458. Retrieved May 31, 2013. Calhoun engaged William A. Weaver, the superintendent of the 1840 census, to review the figures and check them against related data from the 1830 census. Ibid. Weaver reported that he had examined "each specification of error" and concluded that the memorialists had themselves erred in their claims. While there doubtless had been minor errors, he said, there had been no glaring methodological mistakes as charged. See William Edwin Hemphill, ed., The Papers of John C. Calhoun: 1845, Columbia, S.C.: Univ. of South Carolina Press, 1993, vol. 21, p. 156.