Afghanistan Poll: Note on Methodology
National Afghanistan survey involved a random sample of 1,534 Afghan adults.
Feb. 9, 2009 — -- This survey was conducted for ABC News, the BBC and ARD by the Afghan Center for Socio-Economic and Opinion Research (ACSOR) in Kabul, a subsidiary of D3 Systems Inc. in Vienna, Va. Interviews were conducted in person, in Dari or Pashto, among a random national sample of 1,534 Afghan adults from Dec. 30, 2008 to Jan. 12, 2009.
A total of 194 sampling points were distributed proportional to population size in each of Afghanistan's 34 provinces, stratified by urban/nonurban status. Sampling points were then distributed to randomly selected districts within provinces, also proportionate to population size; and lastly to randomly selected villages or neighborhoods within those districts, by simple random sampling. Sources for population parameters were population projections from the Afghan Central Statistics Office.
Half the sampling points were designated for male interviews, half for female interviews. Male respondents were interviewed only by male interviewers, female respondents only by female interviewers. Residences were selected within each settlement by random route/random interval and respondents were selected within residence by Kish grid.
In addition to the national sample, oversamples were drawn in Balkh, Helmand, Herat, Kandahar, Kunduz, Logar, Nangarhar and Wardak provinces to allow for more reliable analysis in those areas. The sample was weighted by population of province to correct for the oversample.
In order to reduce the design effect due to clustering, where randomly drawn male/female sampling points fell within close proximity to each other in districts with fewer than 20,000 residents, the number of sampling points was doubled, also by random selection, and the number of interviews per point was halved, from 10 to five. Of the total of 194 sampling points, 76 were assigned in this manner.
Interviews, which averaged 33 minutes in length, were conducted by 176 interviewers (86 female and 90 male) in 34 supervised teams. All interviewers were trained and all had experience on previous ACSOR field projects. Six percent of interviews were directly observed by field supervisors and an additional 12 percent were back-checked in person afterwards, with further logical controls conducted at ACSOR offices in Kabul.
The survey had a contact rate of 91 percent and a cooperation rate of 95 percent for a net response rate of 86 percent. The impact of clustering on the sample produces an estimated design effect of 1.13, for a total margin of sampling error of 2.5 percentage points at the 95 percent confidence level.