Iraq Poll: Note on Methodology

March 16, 2009 — -- This survey was conducted for ABC News, the BBC and NHK by D3 Systems of Vienna, Va., and KA Research Ltd. of Istanbul, Turkey. Interviews were conducted in person, in Arabic or Kurdish, among a random national sample of 2,228 Iraqis aged 18 and up from Feb. 17-25, 2009.

Four-hundred-forty-six sampling points were distributed proportionate to population size in each of Iraq's 18 provinces, then in 102 districts within the provinces, then by simple random sampling among Iraq's nearly 11,000 villages or neighborhoods, with urban/rural stratification at each stage. Four sampling points were substituted for security reasons.

Maps or grids were used to select random starting points within each sampling point, with household selection by random route/random interval and within-household selection by the "next-birthday" method. An average of five interviews were conducted per sampling point.

Interviews were conducted by 133 trained Iraqi interviewers with management from 26 supervisors and quality control personnel. Fifty-four percent of the interviews were subject to quality control: Thirty-three percent by direct observation by supervisors and control team members, 11 percent by in-person back-checks by supervisors and 11 percent by regional field managers and central office control staff.

In addition to the national sample, oversamples were drawn in Anbar province, Sadr City, Basra city, Kirkuk city and Mosul to allow for more reliable analysis in those areas. Population data came from 2005 estimates by the Iraq Ministry of Planning. The sample was weighted by sex, age, education, urban/rural status and population of province.

The survey had a contact rate of 93 percent and a cooperation rate of 67 percent for a net response rate of 62 percent. Including an estimated design effect of 1.49, the results have a margin of sampling error of 2.5 percentage points at the 95 percent confidence level.

SUNNI/SHIITE – Given the attitudinal differences between Shiite and Sunni Arabs in Iraq, there's interest in the relative sizes of these two groups. We find no official Iraqi estimate of the country's Sunni vs. Shiite Arab populations and no authoritative source of empirical data on the subject.