Psych HL - 2.1, Sampling Methods

Random

Every member in the target population has an equal chance of being picked. This can help reduce selection bias, but may lead to subgroups of the target population not being represented equally.

Convenience/Opportunity

Selecting people who are readily available and willing to participate in the study. Easy for researchers to obtain, but it’s not random, so the target population may not be fully represented.

Volunteer

Collecting people who sign up for the study willingly. Easy for researchers to obtain, but it’s hard to assess if results obtained in this study would apply to people outside of it.

Purposive

Selecting people who have specific characteristics required for the study. This allows for the methodology to align with the aim of the study, but it’s not random, so the target population may not be fully represented.

Snowball

Participants who are already in the study help recruit more participants through their own social networks. This allows researchers to access hard-to-reach groups for data, but it’s not random, so the target population may not be fully represented.