As we continue to learn about different research designs and concepts, it’s impo

As we continue to learn about different research designs and concepts, it’s important to recognize differences among designs. For each of the following designs (a) give an example, (b) identify the major threats to validity, and (c) state the limits on the conclusions that can be drawn.
Single-group, posttest-only design
Ex post facto design
Single-group, pretest-posttest design
Pretest-posttest, natural control-group design Reference: Graziano, A. M., & Raulin, M. L. (2012). Research methods: A process of inquiry (8th ed.). New York, NY: Pearson. ( you can use other refernces)