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. 2012 Apr 27:11:12.
doi: 10.1186/1476-072X-11-12.

A two-stage cluster sampling method using gridded population data, a GIS, and Google Earth(TM) imagery in a population-based mortality survey in Iraq

Lp Galway  1 , Nathaniel Bell, Al Shatari Sae, Amy Hagopian, Gilbert Burnham, Abraham Flaxman, Wiliam M Weiss, Julie Rajaratnam, Tim K Takaro
Affiliations

A two-stage cluster sampling method using gridded population data, a GIS, and Google Earth(TM) imagery in a population-based mortality survey in Iraq

Lp Galway et al. Int J Health Geogr. .

Abstract

Background: Mortality estimates can measure and monitor the impacts of conflict on a population, guide humanitarian efforts, and help to better understand the public health impacts of conflict. Vital statistics registration and surveillance systems are rarely functional in conflict settings, posing a challenge of estimating mortality using retrospective population-based surveys.

Results: We present a two-stage cluster sampling method for application in population-based mortality surveys. The sampling method utilizes gridded population data and a geographic information system (GIS) to select clusters in the first sampling stage and Google Earth TM imagery and sampling grids to select households in the second sampling stage. The sampling method is implemented in a household mortality study in Iraq in 2011. Factors affecting feasibility and methodological quality are described.

Conclusion: Sampling is a challenge in retrospective population-based mortality studies and alternatives that improve on the conventional approaches are needed. The sampling strategy presented here was designed to generate a representative sample of the Iraqi population while reducing the potential for bias and considering the context specific challenges of the study setting. This sampling strategy, or variations on it, are adaptable and should be considered and tested in other conflict settings.

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Figures

Figure 1
Figure 1
Map of Iraq illustrating clusters in first sampling stage with governorate borders in red. Inset is Baghdad area.
Figure 2
Figure 2
Illustrative example of Starting Household selection and map used to locate Starting Household. A. Illustrative cluster; B. Illustrative cluster with sampling grid; C. Illustrative starting household. The cluster and selected household shown here are for illustrative purposes only to protect the identity of households that participated in the survey. The image of the sampling grid shows only a small proportion of the entire grid. The imagery is from Google EarthTM.
See this image and copyright information in PMC

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