This module is part of the 2027 curriculum. You are following the 2026 curriculum, where it is not taught in this form. Switch if you are sitting the exam under the 2027 curriculum.
Lesson 8 of 22 · 12 min
Convenience and judgmental sampling, and choosing a method
Non-probability samples are chosen by convenience or expert judgment: quick and cheap, but at real risk of not representing the population.
In short
- Non-probability methods rely on the researcher's selection, not on a fixed random process, so not every member has an equal chance of being chosen.
- Convenience sampling: use what is easiest to access. Fast and low cost, ideal for a pilot study, but the sample may not represent the population, so accuracy can be limited.
- Judgmental sampling: an expert handpicks members. Useful under time pressure or when expertise is critical (e.g. auditing), but exposed to the researcher's bias.
- Probability methods let chance alone drive sampling error; non-probability methods add the risk of a systematically unrepresentative sample.
- Match the method to the goal: inference about a population → probability sampling; index replication → stratified; vast population on a budget → cluster; quick first look → convenience.
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