Figure 2.

Urinalysis results across consecutive mandatory urine samples for Completers (n = 91). Each participant is represented by a row of symbols. The symbols shown in each row represent samples that were negative for both opiates and cocaine (filled squares), negative for opiates and positive for cocaine (gray squares), positive for opiates and negative for cocaine (gray triangles), positive for both opiates and cocaine (unfilled triangles), missing (blank), or excused (“e”). Phase lines represent the administration of each abstinence-reinforcement contingency.