2. Approaches When N nk ≠
2.1. Circular Systematic Sampling (CSS)
Lahiri (1952) [7] suggests the Circular Systematic Sampling (CSS) which consists of taking a random number
from 1 to N and selecting the unit corresponding to this random start and every th k unit thereafter in a cyclical
manner until a sample of n units is obtained, k being the nearest integer to N n , i.e. If r is a random number selected
from 1 to N, the sample consists of the units corresponding to the number