<qa>  What is the goal of this study?The objective of this study is to compare the efficacy and tolerability of DITROPAN XL 10 mg once-daily and DETROL LA 4 mg once-daily in the reduction of urge urinary incontinence episodes in female patients with overactive bladder. This is a multicenter, randomized, double-blind, parallel-group study with two active treatments. Screened patients are qualified for the study based on information obtained from seven consecutive 24-hour urinary diaries completed during the Baseline Week, and other eligibility criteria. Qualifying patients receive 12 weeks of treatment with DITROPAN XL or DETROL LA, with clinical visits at the end of Weeks 2, 4, 8, and 12. 