PDF, 1536K - Measure DHS

A.4 SAMPLING FRAME
The Ethiopia DHS used the sampling frame provided by the list of census enumeration areas
(EAs) with population and household information from the 1994 Population and Housing Census. A
proportional sample allocation was discarded because this procedure yielded a distribution in which 80
percent of the sample came from three regions, 16 percent from four regions and 4 percent from five
regions. To avoid such an uneven sample allocation among regions, it was decided that the sample
should be allocated by region in proportion to the square root of the region’s population size. Additional
adjustments were made to ensure that the sample size for each region included at least 700 households,
in order to yield estimates with reasonable statistical precision.
A.5 SAMPLE SELECTION
The sample for the survey is based on a two-stage, stratified, nationally representative sample
of households. At the first stage of sampling, 540 2 EAs, 139 in the urban areas and 401 in the rural
areas, were selected using systematic sampling with probability proportional to size.
A complete household listing operation was carried out in all the selected EAs to provide a
sampling frame for the second-stage selection of households. Global Positioning System (GPS) readings
were taken at each EA to enable the linkage of DHS data with other data collected in the same localities.
Sketch maps were constructed to identify the relative position of housing units in an EA to help
interviewers locate selected households during fieldwork. At the second stage of sampling, a systematic
sample of 27 households per EA was selected in all the regions to provide statistically reliable estimates
of key demographic and health variables.
The survey was designed to obtain completed interviews of 14,000 women age 15-49. In
addition, all males age 15-59 in every fifth household were interviewed, to obtain a target of 2,700 men.
In order to take nonresponse into account, a total of 14,642 households nationwide were selected.
A.6 SAMPLING PROBABILITIES
For each urban or rural area in a region, the first stage of selection of EAs was done
systematically with probability proportional to size. This can be mathematically expressed as:
where
P 1i = (a * MOS i ) / (E i MOS i )
a
MOS i
E i
MOS i
is the number of allocated EAs for selection in the urban or rural area of the
region,
is the number of households in the i th EA according to the 1994 Census, and,
is the total number of households in all the urban or rural areas of the
region.
2 During fieldwork, an entire EA in Dire Dawa was demolished, reducing the total number of EAs covered to 539,
and reducing the number of urban EAs to 138.
182 * Appendix A