A between groups design has two study participants who are placed into two different groups (one group takes a new medication and one does not). Then, after the study is completed, the researcher compares how each study participant’s pain levels change after they have taken each medication and determines whether or not there is a difference between the two groups. Within groups research design:
If the researcher wishes to compare two different conditions within one study participant (for example, if they are studying how two different medications affect blood sugar levels), they can conduct a within-groups design. For this design, each study participant takes one medication (for example, one pill) that may affect blood sugar levels differently than another medication (for example, one pill) that may not affect blood sugar levels differently than another medication (for example, one pill). After the study is completed, the researcher will compare how each study participant’s blood sugar levels change after they have taken each medication.