Sampling

Concept

Terminology

Population: The complete group of people, objects, or events that we want to learn something about.

Sample: A subset of a population.

Simple Random Sample (SRS): A sample drawn uniformly at random without replacement.

• "Uniformly" means every individual has the same chance of being selected.
• "Without replacement" means we won't pick the same individual more than once.

Convenience Sample: A sample made up of people who are easy to reach.

Sampling Strategy

• Good idea ✅: Select individuals at random.

• Bad idea ❌: Using convenience samples, which often contain hidden sources of bias.