Cluster sampling is a statistical technique that breaks down the population to be surveyed into segments or clusters. Subsequently, a limited number of clusters are surveyed. If the population is large, random samples may be identified from the selected clusters. Alternately, the entire population in the selected clusters may be studied.
What does cluster sampling mean?
Cluster sampling involves dividing the population into segments. This technique is commonly used when the population is spread over a large geographical area.
For example, a country’s primary educational system may need to be surveyed. The population may consist of 10,000 schools. The schools may be divided into clusters based on the city in which they are located. This would simplify the process.
All the schools in the selected cities (clusters) could be surveyed. If the number of these schools is high, a random sampling of schools in each of the chosen cities may be made part of the survey.
Why use cluster sampling? This is a useful technique if you are working with a limited budget and a large population. Cluster sampling allows you to increase the sample size. However, the clusters that have been selected may influence the results that you get. That’s why it’s essential to be sure that the cluster selection method is unbiased.
Example of cluster sampling
Evodia Inc., a consumer goods company that sells to distributors and retailers across the United States, plans to launch a new product targeted at the budget segment. However, before the launch of its new soap, it wants to conduct a market survey to find out whether it be will be popular with buyers.
The firm is working on a restricted budget. Evodia’s market research company advises it to go in for cluster sampling. Ten states across the country are selected at random. Subsequently, the soap is marketed on a test basis to middle-income and low-income groups in these states.
Cluster sampling allows Evodia to conduct its market survey at a low cost. The feedback that it receives from customers is positive, and the company decides to go ahead with a nationwide launch.
Cluster sampling involves selecting groups rather than individual units. Although this method is an economical option, the process used for selecting the clusters may influence the results.