Non-probability sampling is a sampling technique where the samples are gathered in a process that does not give all the individuals in the population equal chances of being selected. A purposive sample is a non-probability sample that is selected based on characteristics of a population and the objective of the study. Purposive sampling is also known as judgmental, selective, or subjective sampling. Simple random sampling is a probability sampling method where the elements are selected in a random manner so that every item in the population stands an even chance/probability of being selected in the sample. Systematic sampling is a probability sampling method where the elements are chosen from a target population by selecting a random starting point and selecting other members after a fixed ‘sampling interval’. Sampling interval is calculated by dividing the entire population size by the desired sample size. Stratified sampling is a probability sampling method wherein items are selected from different strata of the population, rather than at random from the whole population, in order that it should be representative.