Selection bias can be a potential threat to internal validity when subjects are assigned to groups
A) in a random fashion
B) on the basis of different criteria for the different groups
C) in a way that insures that similar people are in each group
D) none of the above

Question

Quizplus · Accepted Answer

Selection bias occurs when subjects are assigned to groups based on different criteria for each group, leading to systematic differences between groups that can threaten the internal validity of the study. Random assignment (A) and ensuring similar people are in each group (C) are methods to prevent selection bias, not causes of it.

Selection Bias Can Be a Potential Threat to Internal Validity