Sampling
Sampling Procedure
The 2008 Mongolian Reproductive Health Survey (RHS) has a nationally representative sample of 8382 households, in which 9402 women of reproductive age 15-49 years and a subsample of 3362 husbands were interviewed.
Complete national representation is key for any sample to give results that are truly generalizable to an entire population. The current RHS used the same sampling techniques as the 1998 and 2003 surveys to achieve national representation with minimal sampling errors. The survey was conducted using a two-stage sampling method, which gives an equal probability of selection of households. As this is the same method used in previous surveys, this means that the data are fully comparable with the RHS 1998 and RHS 2008 data sets. The sample frame was comprised of the listings of households prepared annually by bags and horoo across the country. Activities, such as improving household listing, designed for improving the quality of data of the first-stage sample frame were conducted in the fourth quarter of 2007 and the first quarter of 2008. Based on that the actual sampling was based on data from the first half of 2008.
It was determined from the experience of RHS 1998 and RHS 2003 and the similar surveys conducted in other countries that 25 to 30 households per cluster would provide an optimum representation; therefore, 30 households were selected for a cluster. It was decided select to 8,400 households (the lower limit was 7,560), which is 1.3 percent of all households in the country. Dividing this number by the 30 households by cluster gave the result of needing 280 primary sampling units (PSUs). Baghs and horoos were chosen as the primary sampling units (PSUs), resulting in a total of 1,676 PSUs. These PSUs were stratified implicitly by aimag and soum, and the selection of the 280 sample PSUs (or clusters) was done systematically with a random start and probability proportional to the number of registered households in each PSU. Households were then selected systematically with a random start within each PSU, using an interval directly proportional to the number of households in the PSU. The selected households were interviewed using the household questionnaire. All women between the ages of 15 and 49 (inclusive) who slept in the household's dwelling the night prior to the interview were eligible to be interviewed using the women's interview schedule. Three husbands out of every five married women were interviewed in each PSU using the husband's interview schedule.
Distribution of the RHS Household Sampling by Aimag,
Mongolia 1998, 2003, 2008
Number of households 2008
1998 2003 Number of
households Clusters
Arhangai 300 390 330 1-11
Bayan-Olgii 200 300 270 12-20
Bayanhongor 250 330 270 21-29
Bulgan 175 240 210 30-36
Gobi-Altai 175 240 210 37-43
Dornogobi 125 180 180 44-49
Dornod 200 240 270 50-58
Dundgobi 150 180 150 59-63
Zavhan 250 300 270 64-72
Ovorhangai 350 420 390 73-85
Omnogobi 125 180 180 86-91
Suhbaatar 150 210 180 92-97
Selenge 250 330 300 98-107
Tov 275 330 330 108-118
Uvs 249 300 240 119-126
Hovd 200 300 270 127-135
Hovsgol 325 450 420 136-149
Hentii 200 270 240 150-157
Darhan-Uul 250 270 300 158-167
Ulaanbaatar 1607 2610 3060 168-269
Orhon 149 300 300 270-279
Govisumber 50 30 30 280
Total 6005 8400 8400
Weighting
Sampling metod RHS2008 is a nation wide.
