What is the term for sampling that allows individuals to be chosen only once?

The term that describes sampling where individuals can be selected only once is simple random sampling without replacement. In this method, once an individual is chosen for the sample, they are not returned to the pool of potential selections, meaning that each selection has to be from a decreasing pool of available individuals. This is important for accurately representing a population, as it eliminates duplication of individuals in the sample, ensuring that the sample reflects a more diverse set of observations.

This type of sampling is particularly useful when the goal is to achieve a representative subset of the larger group without redundancy. For example, if you want to survey people in a community, selecting the same person more than once would not provide new information, and thus, sampling without replacement gives a clearer picture of the whole community's views.

Other methods of sampling, such as simple random sampling with replacement, allow individuals to be selected multiple times since each selected individual is "replaced" back into the pool for subsequent selections. Meanwhile, stratified sampling involves dividing the population into subgroups and then sampling from those subgroups, and cluster sampling focuses on sampling entire groups. However, none of those approaches specifically restrict individual selection to a single instance, which is the defining characteristic of simple random sampling without replacement.