Abstract
Most of the statistical methods have been devised for the purpose of applying to the simple random samples. However, it is often difficult to carry out simple random sampling strictly in the actual surveys. So some analysts apply the techniques, which are generally utilized, to the obtained sample without examining the sampling methods. In this paper, we discuss the effects of disagreement between the sampling methods and the estimators on the estimation of a population mean. As a result some pieces of advice on the way to check it are pointed out.
