Population is the entire aggregation of cases that meet the designated set of criteria. It includes a complete set of persons or objects that possess same characteristics that is of interest to the researcher. The population usually is described as Target population which is also called the universe, is composed of entire group of people or objects to which the researcher w~shes to generalize the findings of a study, target population consists of people or things that meet the designated set of criteria of interest to researcher. Population is not restricted to human subjects. A population might consist of all the hospital records on file or all blood samples. The researcher usually samples from an available group, calledqthe accessible population or study population. The researcher needs to identify the accessible population from which generalization of the study finding can be drawn. The conclusions of research study are based on data obtained from accessible population and the statistical inferences should 60 be made only to the group from which sample was randomly selected.