↑See http://www.cso.ie/census and http://www.histpop.org for post 1821 figures, 1813 estimate from Mason's Statistical Survey. For a discussion on the accuracy of pre-famine census returns see J.J. Lee "On the accuracy of the Pre-famine Irish censuses", Irish Population, Economy and Society, eds. J.M. Goldstrom and L.A. Clarkson (1981) p.54, and also "New Developments in Irish Population History, 1700–1850" by Joel Mokyr and Cormac O Grada in The Economic History Review, New Series, Vol. 37, No. 4 (Nov. 1984), pp. 473–488.