Sampling Procedure
Sample design
A Stratified Two - Stage Sampling was adopted for the survey. Provinces were constituted strata. The primary and secondary sampling units were blocks for municipal areas / villages for non - municipal areas and private households / persons in the special households respectively.
Stratification
Provinces were constituted strata. There were altogether 76 strata. Each stratum was divided into two parts according to the type of local administration, namely municipal areas and non - municipal areas.
Selection of primary sampling unit
The sample selection of blocks / villages were performed separately and independently in each part by using probability proportional to size - total number of households. The total sample blocks / villages was 5,796 from 109,966 blocks / villages.
The total number of sample blocks / villages selected for enumeration by region and type of local administration was as follows :
Bangkok Metropolis, total number of sample enumeration areas -> 312, number of sample enumeration in municipal area -> 312
Central (excluding Bankok Metropolis), total number of sample enumeration areas -> 1968, number of sample enumeration in municipal area -> 1080, number of sample enumeration in non-municipal area -> 888
North, total number of sample enumeration areas -> 1236, number of sample enumeration in municipal area -> 696, number of sample enumeration in non-municipal area -> 540
Northeast, total number of sample enumeration areas -> 1296, number of sample enumeration in municipal area -> 720, number of sample enumeration in non-municipal area -> 576
South, total number of sample enumeration areas -> 984, number of sample enumeration in municipal area -> 528, number of sample enumeration in non-municipal area -> 456
Selection of secondary sampling unit
Private households were our ultimate sampling units. A new listing of private households were made for every sample block / village to serve as the sampling frame. In each sample block / village, a systematic sample of private households were selected with the following sample size :
Municipal areas : 15 sample households per block
Non - municipal areas : 12 sample households per village
Before selecting sample private households in each sample block / village, the list of private households was rearranged by household ' s size - member of the household and type of economic household.
All special households located within the sample areas were included in the sample and the persons in the special household were systematically selected for the interviewing.
The total number of sample private households selected for enumeration by region and type of local administration was as follows :
Region / Stratum
Bangkok Metropolis, total number of households -> 4680, households in municipal area -> 4680
Central (excluding Bankok Metropolis), total number of households -> 26856, households in municipal area -> 16200, households in non-municipal area -> 10656
North, total number of households -> 16920, households in municipal area -> 10440, households in non-municipal area -> 6480
Northeast, total number of households -> 17712, households in municipal area -> 10800, households in non-municipal area -> 6912
South, total number of households -> 13392, households in municipal area -> 7920, households in non-municipal area -> 5472