Purposive sampling also knows as judgmental, selective, or subjective sampling, reflects group of sampling techniques that rely on the judgment of the researcher. This sampling procedure is always prefer the choice of the researcher. Judgmental sampling is completely opposite of probability sampling such as simple random sampling, stratified sampling, systematic sampling, cluster sampling, multi-stage sampling. So the perposive sampling is a non-probability sampling.
According to wikipedia,
“Judgment sample, or Expert sample, is a type of random sample that is selected based on the opinion of an expert. Results obtained from a judgment sample are subject to some degree of bias, due to the frame and population not being identical. The frame is a list of all the units, items, people, etc., that define the population to be studied. Judgement sampling is the noble to provide detailed information about the difficulties in obtaining the distinction. A random sample would provide less bias, but potentially less raw information. The downfalls of this system are significant as any non-random sample brings bias into question, which limits the types of statistical analyzes you may reasonably perform, and there are considerable limits to an experts ability to choose a good sample.”
Example of purposive sampling
Application of purposive sampling
- It is a simple method of sampling.
- Systematic samples are convenient to draw and excuse.
- This method is comparatively economic isn terms of time, labour and money.
- This information doesn’t represent the population.
- Unwillingness to help and co operate
- Selecting informants who are convenient for study.
- Sampling bias always exist in this sampling.
Types of purposive sampling
- Judgmental sampling.
- Quota sampling.