What is a probability sample?

A probability sample is a type of sample from a population in which each unit of the population has an equal chance of being selected. This type of sample is considered to be the most reliable and valid because, through random selection, it allows the researcher to make generalizations, or draw conclusions, that can be applied to the total population. In other words, the study results will accurately reflect the characteristics of the entire population, rather than just the sample being studied.