Within cluster randomized trials no algorithms exist to generate a full enumeration of a block randomization, balancing for covariates across treatment arms.
The total number of Enumeration Blocks and Living Quarters (LQ) that was selected varies according to districts.
In urban areas, the clusters were selected from a list of enumeration blocks maintained by the Federal Bureau of Statistics and considered as the primary sampling unit (PSU).
Participants were recruited into the study using a three-stage cluster-sampling design: a) selection of census blocks, or groups of blocks; b) enumeration and random selection of households within selected areas; and c) random selection of household occupants.
The stages of sample selection were a) selection of census blocks, or groups of blocks; b) enumeration and random selection of households within selected areas; and c) random selection of study participants within households.
A total of 160 clusters are randomly selected based on blocks enumeration of the national census of 1996 by the Iranian Statistics Center.
At the second stage, a list of census enumeration blocks (CEBs) in every selected ward formed the sampling frame from which one CEB was selected by PPS from each selected ward.
The selection procedure for the houses to be sampled involved the enumeration of each house in the block, and the selection of five houses on each side, with the previous consent of the householder.
The five sites in Male' each consisted of three contiguous enumeration blocks and were selected randomly from among enumeration blocks in the 1995 census.
The census data were a sample drawn from the population - from each district of the country, 20% of the rural and 50% of the urban enumeration blocks (EB) were selected using systematic sampling.
Similar to 2002, a multistage sampling design was used to select households using the master sampling frame of census enumeration blocks from the 2004 Jordan census to select the sample of blocks, or primary sampling areas, from which households were selected.
