Convenience sampling is used by researchers to select research participants based on their accessibility. Data is collected from conveniently available participants. The best situation to use this method is when an evaluator wants to gather information about a product or service quickly (Royse et al., 2016). This technique is most suitable for several reasons. First, it gives insights within a shorter period compared to other methods. Second, the convenience method is inexpensive. Third, it is easy to apply considering that the sample is readily available. It is also easy to apply because there are few rules to follow.
Purposive sampling is a non-probability sampling method where researchers use their judgment in choosing study participants. This method is most appropriate where a researcher wants to reach a certain target quickly. For example, it would be appropriate when selecting participants for a case study research design. This is considering that it will help the researcher access the targeted group (Royse et al., 2016). In a case study research design, the researcher would select participants who fit a particular profile quickly. Again, in a case study research, sampling for proportionality is not a key concern. This makes purposive sampling an appropriate method for such research designs.
Random sampling technique is a sampling method in which all members of a population have an equal chance of being selected as study participants. It is most suitable in situations where a larger population is involved. For example, if a researcher wants to study perceptions of a service from a larger population, purposive sampling would help choose a smaller sample size from which research can be done and findings generalized (Fitzpatrick et al., 2022). This technique is suitable in such situations because it is impossible to include all eligible participants with a larger population.
Posavac, E. J. (2011). Program evaluation: Methods and case studies (8th ed.). Boston, MA: Pearson, Prentice Hall.
Royse, D., Thyer, B. A., & Padgett, D. K. (2016). Program evaluation: An introduction to an evidence-based approach (6th ed.). Boston, MA: Cengage.