The statistical representation of Wave 1 is:
- At district level, between 5% and 7% margin of error within a 95% confidence interval.
- At the sub-district level, between 7% and 10% margin of error within a 95% confidence interval.
- At the tribal confederation group level per sub-district, between 7% and 10% margin of error within a 95% confidence interval (only groups categorized as major and minor).
Weighting the Sample
Sampling was stratified by sub-district and tribal affiliation to ensure large-enough sample sizes for each of these units of analysis.
However, so that survey results are representative of the actual population size of each tribal confederation group, sub-district, and district, a three-step weighting methodology was applied:
- Step 1: A sample size of 100 surveys was drawn from each confederation tribal group categorized as major, and 100 from the rest. The sample was then distributed equally across the tribes within each group. Groups categorized as non-negligible were also sampled to give indicative results (not statistically representative).
- Step 2: The sample was then weighted: Weighting the population size for each district and sub-district adjusted the sample size to the actual population for each administrative unit. The population figures and weights were based on the estimated district and sub-district population sizes reported in the 2012 World Bank population estimates and the population return figures reported by IOM Iraq’s Displacement Tracking Matrix (DTM).
- Step 3: The final step consisted of ensuring that results were given equal balance to the views of male and female respondents within the sample. This assumes that the population is equally distributed between both groups.
Qualitative methods
Findings were supplemented by additional qualitative work. This included key informant interviews with government (e.g. mayors or mayor office representatives) and local civil society organizations. It also included validation sessions with community members.