 Figure 2  (left part) presents a plausible DAG for our running example, including the variables Treatment, Gender, and Success. There are two ways in which Treatment provides information about Success. One is that people who take the treatment may be more (or less) likely to recover as a result of having taken it. The other is that learning that someone took the treatment provides information about whether they are likely to be male or female, and this information is relevant to determining whether they will recover regardless of whether they took the treatment.