In contrast to radio, most of our regular television programming does not have built-in breaks appropriate for fund-raising segments. Therefore, OPB supplements its regular programming with shows produced especially for membership drives. Since we aim to have as successful a fund-raising period as possible, we air specials that attract large audiences, including many who are not regular viewers of OPB, and keep the length of our drives to the minimum that will allow us to reach our financial goals. OPB's experience, as well as that of other public broadcasting stations, has shown that a mix of special and regular programming results in the most effective membership drive schedule. Once a drive has ended, we evaluate results and viewer response, and make changes as needed.