Probability sampling. The most rigorous sampling strategy for quantitative research is probability sampling. In probability sampling the researchers selects individuals (or units, such as schools) from the population through a random process so that each individuals has a known chance (or probability) of being selected. You can think of probability sampling as the researcher putting everyone’s name from the population into a hat and and drawing out names at random to participate in the study. The most common example of this sampling strategy is random sampling where the researcher selects participants at random from the larger group. Another example is stratified random sampling where the researcher first stratifies the population into groups (such as boys and girls) and then randomly selects participants from each group to ensure the groups are represented in the sample.