Understanding Non-Probabilistic Sampling
Non-probabilistic sampling refers to sampling methods where not all individuals have a chance of being selected. One of the prominent types of non-probabilistic sampling is Purposive or Judgement Sampling.
What is Purposive or Judgement Sampling?
- This method involves selecting subjects based on specific characteristics or criteria defined by the researcher.
- Researchers use their judgment to choose participants who are most likely to provide valuable information related to the research objectives.
Key Characteristics of Purposive Sampling:
- Targeted Selection: Participants are selected deliberately to meet certain criteria, ensuring that they possess certain attributes relevant to the study.
- Expertise Focus: Often used in qualitative research where the researcher seeks insights from individuals with specific expertise or experiences.
Why is it Non-Probabilistic?
- In purposive sampling, the selection process is subjective. Researchers determine who to include based on their own criteria rather than random selection.
- This contrasts with probabilistic sampling methods, such as Simple Random Sampling, Stratified Sampling, or Systematic Sampling, where every individual in the population has a known and equal chance of being selected.
Implications in Research:
- While purposive sampling allows for in-depth exploration of specific issues, it may introduce bias, making it less generalizable to the broader population.
- It is particularly useful in exploratory research where the aim is to gain insights rather than to make statistical inferences.
In summary, purposive or judgement sampling is a non-probabilistic method that relies on the researcher's discretion, making it distinct from methods that ensure equal selection probability for all individuals in the population.