Week 4 – Discussion 1

Experimental Designs

Two key factors, the inclusion of control groups and the utilization of random assignment, distinguish experimental designs from most other designs. Because these designs offer a higher degree of control, experimental designs have much greater internal validity than other methods. Provide examples of both a posttest-only design and a pretest-posttest design. For each design, discuss the major threats to validity and the limits on the conclusions that can be drawn. Discuss the importance of random assignment, and the advantages and disadvantages of using independent group designs over repeated measure designs. Post should be at least 300 words.