Convenience Sample

A Brief Overview of the Sampling Technique

College students seated in a lecture hall represent a commonly used type of research convenience sample.
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A convenience sample is a non-probability sample in which the researcher uses the subjects that are nearest and available to participate in the research study. This technique is also referred to as "accidental sampling," and is commonly used in pilot studies prior to launching a larger research project.

Overview

When a researcher is eager to begin conducting research with people as subjects, but may not have a large budget or the time and resources that would allow for creation of a large, randomized sample, she may choose to use the technique of convenience sampling.

This could mean stopping people as they walk along a sidewalk, or surveying passersby in a mall, for example. It could also mean surveying friends, students, or colleagues to which the researcher has regular access.

Given that social science researchers are also often college or university professors, it is quite common for them to begin research projects by inviting their students to be participants. For example, let’s say that a researcher is interested in studying drinking behaviors among college students. The professor teaches an introduction to sociology class, and decides to use her class as the study sample, so she passes out surveys during class for the students to complete and hand in.

This would be an example of a convenience sample because the researcher is using subjects that are convenient and readily available. In just a few minutes the researcher is able to conduct an experiment with possibly a large research sample, given that introductory courses at universities can have as many as 500-700 students enrolled in a term.

However, this particular sample raises important issues that highlight both the pros and cons of this sampling technique.

Cons

One con highlighted by this example is that a convenience sample is not representative of all college students, and therefore the researcher would not be able to generalize her findings to the entire population of college students.

The students enrolled in the sociology class, for example, could be heavily weighted toward a certain characteristic, like being mostly first-year students, and they may also be skewed in other ways, like by religiosity, race, class, and geographical region, depending on the population of students enrolled at the school.

In other words, with a convenience sample, the researcher is unable to control the representativeness of the sample. This lack of control may cause a biased sample and research results, and thus limits the wider applicability of the study.

Pros

While the results of this study could not be generalized to the larger college student population, the results of the survey could still be useful. For example, the professor could consider the research a pilot study and use the results to refine certain questions on the survey, or to come up with more questions to include on a later survey. Convenience samples are often used for this purpose: to test certain questions and see what kind of responses arise, and use those results as a springboard to create a more thorough and useful questionnaire.

A convenience sample also has the benefit of allowing for a low- to no-cost research study to be conducted, because it uses the population that is already available.

It is also time-efficient, because it allows the research to be conducted in the course of the researcher's everyday life. As such, a convenience sample is often chosen when other randomized sampling techniques are simply not possible to achieve.

Updated by Nicki Lisa Cole, Ph.D.