A judgment sample, also known as an expert or purposive sample, is a type of non-random
sample, where a researcher or expert selects the sample based on who they believe would be most useful or appropriate for the study.
Results obtained from a judgment sample are subject to some degree of
bias
Bias is a disproportionate weight ''in favor of'' or ''against'' an idea or thing, usually in a way that is inaccurate, closed-minded, prejudicial, or unfair. Biases can be innate or learned. People may develop biases for or against an individ ...
and may be hard to
generalize, due to the chosen sample not representing the larger population.
A random sample would provide less bias, but potentially less raw information.
The pitfalls of this system are significant because of bias, limited statistical methods, and limits to an expert's ability to choose a good sample.
References
{{DEFAULTSORT:Judgment Sample
Sampling (statistics)