Steps in Developing a Sampling Plan (3) Step 4: Selecting the Sampling Method Probability samples Samples in which every element of the population has a known, nonzero probability of selection. Nonprobability samples Include the selection of specific elements from the population in a nonrandom mannerSteps in Developing a Sampling Plan （3） • Step 4: Selecting the Sampling Method – Probability samples • Samples in which every element of the population has a known, nonzero probability of selection. – Nonprobability samples • Include the selection of specific elements from the population in a nonrandom manner