Generally, we are interested in representative sample to draw valid conclusions on the population. Such representation can be assured only through random sampling. In random sampling, every unit in the population has a known probability of being included in the sample. The sample is drawn by some method of random selection consistent with these probabilities, and we take into account of these probabilities while estimating the parameters. In random sampling, it is possible to study the bias and error attached to the estimates from different sampling techniques. In this way, much has been reported about the scope, advantages, and limitations of each sampling technique so as to choose the one that suits our sampling job reasonably well.