Unintended differences between the groups in an experiment reflect _____ bias; these differences stem from a failure to follow the principle of random _____.
A) sampling; selection
B) sampling; assignment
C) selection; sampling
D) selection; assignment

Question

Quizplus · Accepted Answer

Unintended differences between groups in an experiment are typically caused by selection bias, where participants are not randomly assigned to groups. This can lead to differences in participant characteristics between groups that can impact the study results. In order to minimize selection bias, random assignment to groups is critical. Option D correctly identifies the bias as selection bias and identifies the correct random principle as assignment.

Unintended Differences Between the Groups in an Experiment Reflect _____