CLUSTER SAMPLING a survey of selected groups within a population the entire population is divided into groups (clusters), and a random sample of these clusters are selected used when certain groups called “natural groupings” are likely to be representative of the entire population

Example: The city of London wants to find out how effective the nutritious meals are in elementary schools across the city and surrounding counties. All elementary students in a local school district 11 different elementary schools in the local school district population groups (clusters)

Example: every student in the 4 selected elementary schools 4 elementary schools from the l1 possible elementary schools obtain a simple random sample sample

Process:  DETERMINE whether or not the population contains “natural” groupings that are representative of the entire population.  DIVIDE the population into groups (clusters).  SELECT a random sample from these clusters.  CONDUCT a survey of the random sample.  ANALYZE the data using statistical techniques.

Advantages: cheap, quick, and easy the researcher is able to use a larger sample size

Disadvantages: least representative of the population out of all the types of probability samples high sampling error caused by limited clusters