%0 Journal Article
%T Choosing a survey sample when data on the population are limited: a method using Global Positioning Systems and aerial and satellite photographs
%A Harry S Shannon
%A Royce Hutson
%A Athena Kolbe
%A Bernadette Stringer
%A Ted Haines
%J Emerging Themes in Epidemiology
%D 2012
%I BioMed Central
%R 10.1186/1742-7622-9-5
%X We randomly sampled Global Positioning System locations in designated areas. A circle was drawn around each location with radius representing 20 m. Buildings in the circle were identified from satellite photographs; one was randomly chosen. Interviewers selected one household from the building, and interviews were conducted with eligible household members.Participants had known selection probabilities, allowing proper estimation of parameters of interest and their variances. The approach was made possible by recent technological developments and access to satellite photographs.Surveys in war zones or other difficult situations have various aims, including estimation of mortality and other harms, population needs and vaccination coverage. Yet such surveys pose considerable challenges for researchers, as there may be little information on which to base the sampling method. Further, in conflict areas risks to the interviewers may limit how information is obtained on the population of interest and how sample data are collected. Particularly when rapid assessment is needed, researchers must balance several desirable properties of surveys: unbiasedness, precision, speed and simplicity.Various approaches have been used to overcome the challenges and still allow valid calculation of point estimates and their confidence intervals. The crucial requirements for the analysis are that: a) the probability of including a sampling unit can be determined; and b) the design effect (that allows for the sampling process) can be computed. These allow the sampling weights to be applied and proper point and variance estimates to be calculated.In this paper we introduce a new sampling method which uses Global Positioning System (GPS) technology and aerial/satellite photography. We used this approach when two particular problems applied: information on the target population was limited and it was considered too risky for interviewers to conduct enumerations on site (enumeration entails list
%K Sampling methods
%K Surveys
%K Surveys in difficult situations
%K Sampling weights
%K Global Positioning Systems
%K Aerial photographs
%K Satellite photographs
%K Lebanon
%U http://www.ete-online.com/content/9/1/5