FIGURE 4.4 • Comparing a Treatment Group to a Wait-List Control Group Participants are randomly assigned to one of two groups, a treatment group and a wait-list control group (although a study could have more than two groups). Generally, the dependent variables, such as intensity of symptoms, are assessed before the treatment period begins, to obtain a baseline. After treatment ends (or after the equivalent number of weeks for the wait-list control group), the dependent variables are again assessed (and may also be assessed later for follow-up) and the data from the two groups are compared.