Cluster sampling is a sampling technique used when "natural" but relatively homogeneous groupings are evident in a statistical population. It is often used in marketing research. In this technique, the total population is divided into these groups (or clusters) and a simple random sample of the groups is selected. Then the required information is collected from a simple random sample of the elements within each selected group. This may be done for every element in these groups or a subsample of elements may be selected within each of these groups. A common motivation for cluster sampling is to reduce the average cost per interview. Given a fixed budget, this can allow an increased sample size. Assuming a fixed sample size, the technique gives more accurate results when most of the variation in the population is within the groups, not between them.
Read more about Cluster Sampling: Cluster Elements, Aspects of Cluster Sampling, Advantage, Disadvantage
Famous quotes containing the word cluster:
“Next week Reagan will probably announce that American scientists have discovered that the entire U.S. agricultural surplus can be compacted into a giant tomato one thousand miles across, which will be suspended above the Kremlin from a cluster of U.S. satellites flying in geosynchronous orbit. At the first sign of trouble the satellites will drop the tomato on the Kremlin, drowning the fractious Muscovites in ketchup.”
—Alexander Cockburn (b. 1941)