Microsoft Word - AMICS-29Jan2013 - Childinfo.org

Within each region, urban and rural stratum, the EAs in the frame were ordered by province, district,
controller code and EA code, in order to provide implicit stratification by province and lower levels
of geography. The specified number of sample EAs was selected from each sampling stratum
systematically with probability proportional to size (PPS), where the measure of size was based on
the estimated number of households in the frame.
A reserve sample of EAs was also selected within each stratum (using the same type of systematic
PPS selection) to be used as possible replacements in extreme cases when the security situation for
an original sample EA made it difficult to enumerate. A total of 102 sample EAs were selected as
possible replacements. During the MICS4 fieldwork, 423 of the original 516 sample EAs were
enumerated, and 26 replacement EAs were enumerated; and the remaining 67 sample EAs were not
replaced. Therefore the final sample in the Afghanistan MICS4 data file includes 449 sample EAs, so
there was an overall reduction in the effective sample size.
Listing Activities
In order to update the second stage sampling frame, a new listing of households was conducted in
each sample EA prior to the selection of households. The enumerators were provided with EA maps,
and they were instructed to list all the households within the EA boundaries.
Selection of Households
Following the listing in each sample EA, the households were sequentially numbered from 1 to n (the
total number of households in each EA). A household selection table was used to select the random
systematic sample of 30 households in the field soon after the listing was completed. Based on the
total number of households listed, the household selection table specified the serial numbers of the
30 households to be selected.
Calculation of Sample Weights
The Afghanistan MICS4 sample is not self-weighting, given that the sampling rates vary by stratum.
Therefore sample weights were calculated and these were used in the subsequent analyses of the
survey data.
The major component of the weight is the reciprocal of the sampling fraction used in selecting the
sample households in that particular sampling stratum (h) and PSU (i):
W
hi
1
f
hi
The term f hi , the sampling fraction for the i-th sample PSU in the h-th stratum, is the product of
probabilities of selection at every stage in each sampling stratum:
fhi
p1
hi
p2hi
where p shi is the probability of selection of the sampling unit at stage s for the i-th sample PSU in the h-
th sampling stratum.
151