Selection bias

Definition

Selection bias occurs when the method of selecting participants or responses in a study leads to results that are systematically different from the target population or truth. It can distort the validity of conclusions drawn about political opinions or behaviors.

Related terms

Sampling error: The discrepancy between the characteristics of a sample and those of the population from which it was drawn.

Response bias: A type of bias that occurs when respondents answer questions untruthfully or misleadingly.

Population:

The entire group about which researchers wish to draw conclusions, often too large to study directly, requiring selective sampling methods