• A probability sampling is a sample in which each individual or household comprising the universe from which the sample is drawn has a known chance or probability of being selected for inclusion in the research. The selection of specific individuals from this universe is done purely by chance, for example, through the use of a table of random numbers. When probability sampling is used, selection of individuals for survey participation continues until the required number of individuals has been selected and interviewed. The primary advantage of probability sampling lies in the ability to generalize finding to the population from which the sample was drawn. Probability samples, for example, are often used in national opinion polls because of the important need to generalize the findings to the total population.