Similarly, giving clients vouchers as reinforcement for abstaining has been established to be a successful method for reinforcing clients in treatment centres. It was found that the value of the voucher and the immediacy with which the voucher was given were associated with larger effects. Overall, support for voucher based reinforcement was found (Lussier, Heil, Mongeon, Badger and Higgins, 2006). Further support for contingency management is found in a meta-analysis conducted by Prendergast, Podus, Finney, Greenwell and Roll (2006) in which they found that in terms of supporting abstinence of substance abuse, contingency management was among the more effective approaches as it allows clients to use other aspects of treatment in the clinic
