1. Randomized field experiments are the strongest research designs for assessing program impact. 2. Environmental variables can also influence results and usually arise from poor research design. 3. There are several different research approaches, or research designs, that qualitative researchers use. 4. Research designs include experimental studies, quasi-experimental studies, pretest-postest designs, and others. 5. You need a coherent research design before you start collecting data. 6. The two basic approaches to research design include between-subjects design and within-subjects design. 7. This is important because much research has been done with single-subject research designs. 8. Or, they may want to know how to implement an appropriate research design. 9. Meta-analysis can be done with single-subject design as well as group research designs. 10. Non-experimental research designs can be broadly classified into three categories.