Research Methodology
Non-Probability Sampling
A sampling technique where samples are gathered in a process that does not give all individuals in the population equal or known chances of being selected.
What is Non-Probability Sampling?
Non-probability sampling relies on the subjective judgment of the researcher or the convenience of access rather than random selection. Because the selection probabilities are unknown, one cannot rigorously calculate sampling error or margin of error.
Why Non-Probability Sampling Matters
It is highly useful for exploratory research, qualitative studies, or when a population is hard to reach, but limits the ability to mathematically generalize findings to the whole population.
Example
A researcher studying the experiences of undocumented immigrants recruits participants through community centers and word-of-mouth.
Common Mistakes
- Applying inferential statistics (like p-values) that assume random sampling to non-probability samples.
- Claiming the sample is 'representative' of the general population.