Stratified sample

Definition

A stratified sample is a sampling method in which the population is divided into distinct subgroups, or strata, that share similar characteristics. A random sample is then taken from each stratum to ensure representation from all groups.

5 Must Know Facts For Your Next Test

1. Stratified sampling improves the precision of the overall sample by ensuring that all subgroups are adequately represented.
2. Strata should be mutually exclusive; an individual or element can belong to only one stratum.
3. Commonly used when researchers want to highlight specific subgroups within the population.
4. The process involves two main steps: dividing the population into strata and then randomly sampling from each stratum.
5. The size of each random sample from a stratum can be proportional to the size of the stratum or equal across all strata.

Review Questions

• What are the primary benefits of using a stratified sample?
• How do you determine the number of samples to take from each stratum?
• Give an example where stratified sampling would be more appropriate than simple random sampling.

Related terms

Simple Random Sample: A sampling method where every member of the population has an equal chance of being selected.

Cluster Sample: A sampling technique where the population is divided into clusters, and a whole cluster is randomly selected for study.

Systematic Sample: $Sampling$ method in which elements are selected at regular intervals from an ordered list.