ABSTRACT
In this chapter we shall consider simple random sampling without stratification of the universe and without the selection of the sample units in different stages; unstratified single-stage simple random sampling is sometimes known as unrestricted simple random sampling. In the next chapter will be shown the use of ancillary information in improving the efficiency of estimators obtained from a simple random sample. We shall often use the abbreviation "srs" for "simple random sample" or "simple random sampling".
