Lee participated in a study that involved the treatment of obsessive-compulsive symptoms. The researchers assessed Lee with others who were participating in the study. However, he received the treatment several weeks later, once the study was complete. Lee most likely was part of a(n) group.

Wait list control group

Explanation:

Lee participated in a study that involved the treatment of obsessive-compulsive symptoms. The researchers assessed Lee with others who were participating in the study. However, he received the treatment several weeks later, once the study was complete. Lee most likely was part of a wait list control group.  The wait list control group are a group of subject who do not receive the treatment during the study but are put on a wait list to receive the treatment after the active treatment group does. The advantage of the wait list control group is that the act as a basis of comparison for active treatment group, they serve as a benchmark.

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