Monday, March 12, 2007

More Plausible Respone Rates

As a follow up to this post, consider this January 2006 poll conducted for World Public Methodological details (pdf):

The survey was designed and analyzed by the Program on International Policy Attitudes for Field work was conducted through D3 Systems and its partner KA Research in Iraq. Face-to-face interviews were conducted among a national random sample of 1,000 Iraqi adults 18 years and older. An over sample of 150 Iraqi Sunni Arabs from predominantly Sunni Arab provinces (Anbar, Diyalah and Salah Al-Din) was carried out to provide additional precision with this group. The total sample thus was 1,150 Iraqi adults. The data were weighted to the following targets (Shia Arab, 55%, Sunni Arab 22%, Kurd 18%, other 5%) in order to properly represent the Iraqi ethnic/religious communities.

The sample design was a multi-stage area probability sample conducted in all 18 Iraqi provinces including Baghdad. Urban and rural areas were proportionally represented. A total of 5 sampling points (4 urban and 1 rural) of the 116 employed were replaced for security reasons with substitutes in the same province and urban/rural classification. Among all the cases drawn into the sample, a 94% contact rate and 74% completion rate were achieved.

The contact and completion rates are almost identical to those of the November 2006 survey. Again, how can these rates be so much lower than those for Lancet II? Now, it could still be that the surveyors employed by WPO (D3 and KA) are not actually surveying people, are just filling out the forms themselves. Anyone doing this is well advised to report plausible contact/completion rates rather than 100%, even though high participation is what the client "wants." Excessive contact/completion rates are the first thing that a wise client checks to ensure against fraud.

But if we assume that D3 and KA have done a proper job --- in nationwide surveys which bracket Lancet II --- it because hard to understand what magic the Lancet survey teams (composed of physicians who, I think, do no other survey work outside of the two Lancet articles) perform in order to produce such high rates. How are the Lancet survey teams able to reach 99% of the intended households while D3/KA can only contact 94%? How are the Lancet teams able to convince virtually everyone they meet (completion rate over 99%) to finish the survey, while D3/KA can't persuade more than 3/4 of the people they meet to finish? Are D3/KA survey teams rude or scary or socially awkward? Are the Lancet teams more friendly or engaging or persuasive?

Perhaps. Yet I think that one survey team is not telling the whole truth, has tried mightily to give its bosses what the bosses want to hear.


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