Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
The selection effect refers to any situation in which individuals self-select into a group, causing a biased sample with non-random distribution of participants.
Related terms
Self-Selection Bias: This occurs when individuals select themselves into a group, leading to biased results. It's like only chocolate lovers voting for the best ice cream flavor - of course, chocolate will win!
This happens when some members of intended population are less likely sampled than others. It's like asking only kids at an ice cream shop what their favorite flavor is - adults' preferences aren't considered.
This is our tendency to search for and favor information that confirms our beliefs while simultaneously ignoring or devaluing information that contradicts our beliefs. Like believing chocolate is universally loved because all your friends (who also love chocolate) agree with you.