Which of the Following Is a Difference Between Between-Groups and Within-Groups

Which of the following is a difference between between-groups and within-groups experimental designs?

A) Random assignment is not necessary for within-groups designs.
B) There is more statistical power for between-groups designs.
C) Between-groups designs provide stronger evidence for causality.
D) Cross-cultural comparisons are easiest for within-groups designs.
E) Between-groups designs are more generalizable.