To Control for History Effects in an Interrupted Time-Series Study

Multiple Choice

To control for history effects in an interrupted time-series study, a researcher includes a comparison group that does not receive the treatment. What is one drawback to using this technique?

A) The comparison group may not be equivalent to the treatment group.
B) The comparison group is usually the same as the treatment group, and it is difficult for participants to "unlearn" the treatment.
C) The comparison group cannot be measured as often as the treatment group.
D) All of the above.