A sample selected by this procedure is termed a systematic sample with a random start r. Therefore, the value
of r determines the whole sample. In other words, this procedure amounts to selecting with equal probability one
of the k possible groups of units (samples) into which the population can be divided in a systematic manner.
Same view was expressed by Raj and Chandhok (1998) [3]. They described systematic sampling as a more
convenient method of sample selection when the units were serially numbered from 1 to N with the assumption
that N = nk, where n is the sample size desired, and k is an integer. A number is taken at random from the numbers
1 to k (using a table of random number/random number generator). Suppose the random number is i, then
the sample contains n units with serial numbers ii ki k i n k , , 2, , 1 + + +− ( ) . Thus, the sample consists of the
first unit selected at random and every k
th unit thereafter. It is therefore called a 1-in-ksystematic sample