In October 2006 Roberts instigated a second study, Mortality after the 2003 invasion of Iraq: a cross-sectional cluster sample survey, using similar methods and increasing the number of households surveyed. The study was also published in The Lancet, and reported: "We estimate that between March 18, 2003, and June, 2006, an additional 654,965 (392,979–942,636) Iraqis have died above what would have been expected on the basis of the pre-invasion crude mortality rate as a consequence of the coalition invasion. Of these deaths, we estimate that 601,027 (426,369–793,663) were due to violence."These figures would be equivalent to 2.5% of the total Iraqi population dying since the start of the war.