PALESTINIAN SOCIETY - Fafo

Selection of Sample PS Us (1st stage)
Sample PSUs were selected from each stratum with a probability
proportionate to population size. In order to determine the 1st stage
inc1usion probability, we need the following variables (all referring to
individuals, Benvenisti estimates):
N(s,k) · = Population total for PSU (s,k)
N(s) = Population total s-th stratum (table A.6)
N = Population total (West Bank)
The fIrst stage inc1usion probability for PSU (s,k) is approximately:
k (s) N (s. k)
(3 1) p ( k) _
.
1 S, - N (s)
in which k(s) is the number ofPSUs selected from the s-th stratum. In
case k( s)= l, the equality above is exact. The approximation accurs for
k( s» 1 , as 2nd order ( and higher) probabilities are assumed negligible.
The number ofPSUs to be selected, the k(s)'s, has been decided like
this in order to avoid situations where the number of sample households
of aPSU exceeds the total numberofPSU households. Thus, for
each stratum both the household sample size, the total numberofPSU s
and the size of the various PSUs have been considered.
In our design the household, not the single individual, is the
ultimate unit of selection. Ifthe average size ofhouseholds is equal for
all PSU s, which is a fairly realistic assumption, (3.1) can be expressed
thus:
(3 2) p ( k) _
k (s) O (s. k)
. 1 S, - O (s)
in which D{s,k) is the total number of households in PSU (s,k), and
D{s) the corresponding total for the s-th stratum.
The number of sample PSU s selected from each of the strata are
shown in table A.8. The total number of sample PSUs is 45.
Seleetion of CeIIs,
Housing Units and Households
As in Gaza, there were no sampling frarnes available for the selection
of households in the West Bank PSUs. Thus it was convenient to
introduce two further sampling stages. At the 2nd stage sample PSUs
were subdivided into cells, and samples of cells were selected by
simple random sampling from the respective PSUs. Housing units
were selected at the 3rd stage, and, fInally, the samples ofhouseholds
(4th stage) were selected from the sample of housing units. The
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