The survey in Pakistan is part of the larger Spring 2011 Pew Global Attitudes survey conducted in 22 countries and the Palestinian territories under the direction of Princeton Survey Research Associates International.
Results for the April survey in Pakistan are based on 1,970 face-to-face interviews of adults conducted April 10 to April 26. Results for the May survey in Pakistan are based on 1,251 face-to-face interviews of adults conducted May 8 to May 15. The questionnaires for the two surveys were identical, with two exceptions. First, the May questionnaire did not include an item asking about confidence in Osama bin Laden. And second, the May questionnaire included a set of questions about the U.S. military operation that killed Osama bin Laden.
Both surveys used a multi-stage cluster sample of all four provinces stratified by province representing roughly 85% of the adult population. The Federally Administered Tribal Areas, Gilgit-Baltistan, Azad Jammu and Kashmir were excluded for security reasons as were areas of instability in Khyber Pakhtunkhwa (formerly the North-West Frontier Province) and Baluchistan — roughly 15% of the population. The samples are disproportionally urban, but the data are weighted to reflect the actual urban/rural distribution in Pakistan. Interviews were conducted in Urdu, Punjabi, Pashto, Sindhi, Saraiki, and Hindko for both surveys and additionally in Chitrali for the April survey and Brahavi for the May survey.
The margin of sampling error for the April survey is ±3.0 percentage points and ±4.0 percentage points for the May survey. For the results based on the full sample, one can say with 95% confidence that the error attributable to sampling and other random effects is plus or minus the margin of error. In addition to sampling error, one should bear in mind that question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of opinion polls.