Control and Experimental Groups

Research studies often use experimental and control groups to look at change relative to an intervention. At the start of a study, researchers identify the population they’re interested in studying (e.g., participants in a certain age range or who have similar lifestyles or health risks). These participants are then randomly assigned to either an experimental group (which gets the intervention) or a control group (which gets a placebo or might be asked to maintain their normal lifestyle). The control group provides a critical comparison group. The experimental group follows a protocol that changes their lifestyle or habits. At the end of the study, researchers can measure any differences between the control and experimental groups to see if the new protocol (dietary change, medication, etc.) caused a change in the outcomes of interest.

Many studies, such as the PAAD-2 study at UNCG, enroll participants who fit certain criteria and then randomly assign them to either a control group or an experimental group. For example, all participants enrolled in the PAAD-2 study are between the ages of 40-65, exercise less than 90 minutes per week, and have a family history of Alzheimer’s disease or dementia. The control group is asked to maintain their current lifestyle of exercising less than 90 minutes per week. The experimental group begins the study’s intervention which includes a walking program and attending virtual strength-training classes. Throughout the study, all participants (control and experimental) undergo cognitive and fitness testing. Any changes in the experimental participants can be compared with those in the control group. Through group comparison s, the PAAD-2 researchers can determine whether the changes were caused by the exercise protocol (if the exercise group outperforms the control group at the post-test) or something else like regular aging (if both groups decline by equal amounts from pre-test to post-test).

When enrolling in a research study, participants sometimes ask if they can be assigned to the experimental group because they believe it will be more beneficial to the research, but the control group is just as beneficial! Regardless of whether a participant is assigned to the experimental group or the control group, they are an invaluable part of that study. The control group is just as important as the experimental group; without it there would be no experiment. Without a control group it is impossible to confidently determine which changes or outcomes are due to the intervention as opposed to being due to some other variable.

Researchers are grateful for all study participants and need people to continue enrolling in studies regardless of which group they may be randomly assigned to. Because of the participants in the PAAD-2 study, the fight against Alzheimer’s presses on daily. Thank you to the PAAD-2 participants and all individuals willing to participate in a research study.