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Quality Quiz:Professor Cleary
Another quiz from Professor Cleary

Congratulations: "B" is correct!

When in doubt, make something up—or at least that seems to be Quinn’s operating principle here, since there is no such thing as a “systematic cluster sample.” He has confused “systematic sample” and “cluster sample,” which are two very different things.

In a systematic sample, the first sample is selected randomly, and subsequent samples follow at evenly spaced intervals until the desired sample size is reached.

Systematic sampling is especially useful with a large population. For example, I once needed to estimate average age for staff members at my university. Records were in a number of separate files in the Human Resources office, numbered from 1 to 1,500. Since I needed a sample size of 150, I went to a table of random digits to select a number from 1 to 10 (it happened to be 7). Then I started the sample with number 7, followed by 17, 27, 37, etc., until I reached 150 samples.

Subtle differences distinguish systematic sampling from cluster sampling:
A cluster sample, on the other hand, separates a population into separate groups called clusters. This approach works best when each cluster represents the characteristics of the entire population. Then samples are selected randomly from each cluster group.

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