Non-probability sampling is a sampling technique in which the researcher selects samples based on the subjective judgment of the researcher rather than random selection.
In non-probability sampling, not all members of the population have a chance of participating in the study unlike probability sampling, where each member of the population has a known chance of being selected.
Non-probability sampling is most useful for exploratory studies like pilot survey (a survey that is deployed to a smaller sample compared to pre-determined sample size). Non-probability sampling is used in studies where it is not possible to draw random probability sampling due to time or cost considerations.
Non-probability sampling is a less stringent method, this sampling method depends heavily on the expertise of the researchers. Non-probability sampling is carried out by methods of observation and is widely used in qualitative research.
Advantages of non-probability sampling
(i) Non-probability sampling is a more conducive and practical method for researchers deploying survey in the real world. Although statisticians prefer probability sampling because it yields data in the form of numbers. However, if done correctly, non-probability sampling can yield similar if not the same quality of results.
(ii) Getting responses using non-probability sampling is faster and more cost-effective as compared to probability sampling because sample is known to researcher, they are motivated to respond quickly as compared to people who are randomly selected.
Disadvantages of non-probability sampling
(i) In non-probability sampling, researcher needs to think through potential reasons for biases. It is important to have a sample that represents closely the population.
(ii) While choosing a sample in non-probability sampling, researchers need to be careful about recruits distorting data. At the end of the day, research is carried out to obtain meaningful insights and useful data.
When to use non-probability sampling?
- This type of sampling is used to indicate if a particular trait or characteristic exists in a population.
- This sampling technique is widely used when researchers aim at conducting qualitative research, pilot studies or exploratory research.
- Non-probability sampling is used when researchers have limited time to conduct researcher or have budget constraints.
- Non-probability sampling is conducted to observe if a particular issue needs in-depth analysis.