Many experimental groups are small and many researchers are not comfortable relying on randomization without empirical verification that the groups are the same, so another common between-subjects des...Many experimental groups are small and many researchers are not comfortable relying on randomization without empirical verification that the groups are the same, so another common between-subjects design is the Pre-test, Post-test Control Group Design (Figure \(\PageIndex{4}\)). With these experimental designs, we worry about external validity, but since we have said we seek the ability to make causal statements, the preference is given to research via experimental designs.
