Selects a balanced cluster sample.
number of clusters.
number of clusters to be selected.
selected only: show the table with selected observations only.
all observations with remark: show the table with all observations and a remark field.
fixed schedule: use a fixed seed in R to generate the same simulation results.
random schedule: use a random seed in R to generate the different simulation results.
Yves Tille, Alina Matei (2015). sampling: Functions for drawing and calibrating samples. R package version 2.7.