Methodology
Population and sample group
The population of this study was Thai children
age from birth to 5 years who live in 76 provinces
of Thailand which can be divided into 5 parts of
Thailand.
Sample Group
From the predicted number of Thai children
age from birth to 5 years in the year 2010 (with
2.5% variation), there would be at least 1,600
children as a sample group. This sample group was
added with another 15% (or 240 children) by
non-replacement sampling, so the sample group in
this study was 2,079 children. From the national
census on the number of children age from birth
to 5 years all over the country, it can be divided
into 5 parts that were; north, central, south,
northeastern, Bangkok Metropolitan City and other
nearby provinces. The sample group from the 5
parts of the country was sampling by using Multi-stage
random sampling as the process mentioned
below:
1. Provinces in each part of the country were
random by the number of children, one province
with the high number of children and another
province with low number of children and the
results were as follows;
I. The provinces in the northern part of
Thailand were Chiang Mai and Lumphun
II. The provinces in the central part of
Thailand were Lop Buri and Sing Buri
III. The provinces in the northeastern part
of Thailand were Khon Kaen and Nongbualamphu
IV. The provinces in Bangkok Metropolitan
City and the province nearby were Bangkok and
Samut Prakan
V. The provinces in the southern part of
Thailand were Songkhla and Surat Thani
VI. Two districts in each random province
were selected by purposive sampling that were
the district in the urban area and another district in
the rural area
2. The number of the sample group was
divided into 60 age groups (the age range is 1
month) (The number of each group can be seen in
Table 1 below)
3. The number o