Which of the following threatens the internal validity of an experiment?

Question

Quizplus · Accepted Answer

Failing to assign participants randomly to conditions threatens the internal validity of an experiment because it can result in selection bias, where the groups may differ in important ways before the experiment begins, making it difficult to determine whether any observed effects are due to the manipulation of the independent variable or pre-existing differences between the groups. A, B, and C also have the potential to threaten internal validity, but not to the same extent as failing to randomize participants into conditions.

Which of the Following Threatens the Internal Validity of an Experiment