=1,2,3,…,k .The mean of the i-th sample is denoted by
̅
.The systematic sampling estimator of the population
mean, µ .The variance of this mean estimator requires some
assumptions as below:
1-When the population values are assumed to be in no
particular order with respect to the variance of the estimator
of the mean is the same as in the case of simple random
sampling. (Aczel, 1989).