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Quality Quiz:Professor Cleary
Another quiz from Professor Cleary

Congratulations: "B" is correct!

Unfortunately, there is no such thing as “convenience random sampling.” As we noted last month, the two types of samples are probability samples and nonprobability samples.

Probability samples: Nonprobability samples:
Simple random sample Judgment sample
Stratified sample Quota sample
Cluster sample Convenience sample
Sequential sample  

A simple random sample, as the table indicates, is a probability sample in which each element of the population has an equal likelihood of being selected for the sample. This approach could provide .information that would allow one to make probabilistic estimates from the sample results. The most common would be to create confidence limits around the sample mean derived from the random sample.

On the other hand, a convenience sample is not capable of producing these outcomes. It is named aptly, since it represents an easy way to derive samples. In an example used in my university introductory statistics class, one might ask a simple yes/no question to the 250 students and ask someone to count the results. For example, with a question such as “Will you vote for ___ for U.S. president?”, it would be easy to survey the group for responses. This is not a scientific survey, since it includes only those students in the College of Business who actually live in Dayton, attend Wright State University, and attend class at 12:00. No valid conclusions about a larger population could be drawn from this sample.

But the approach was certainly convenient.

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