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.