Sampling Methods

STATS Unit 3 Ch. 11

Simple Random Sample (SRS)

A sampling method where every individual AND every possible group has an equal chance of being selected.

How to recognize SRS

Uses random numbers, random name generator, or random selection from a full list.

Stratified Sample

Population is split into groups (strata) based on a shared characteristic; an SRS is taken from each group.

How to recognize Stratified

Groups differ from each other but are similar within themselves (ex: grade level, gender).

Cluster Sample

Population is split into clusters that each resemble the whole population; entire clusters are randomly selected and everyone in those clusters is sampled.

How to recognize Cluster

Select whole groups like classrooms, neighborhoods, teams.

Systematic Sample

Choose a random starting point and then select every kth individual.

How to recognize Systematic

“Every 10th person,” “every 5th name.”

Convenience Sample

Sample people who are easiest to reach.

How to recognize Convenience

Asking friends, people in hallway, cafeteria, etc.

Voluntary Response Sample

People choose themselves to participate by responding.

How to recognize Voluntary Response

Online polls, call

Multistage Sample

Combines multiple sampling methods (ex: choose clusters, then SRS within clusters).