“…In primary-care clinics with many walkin patients and high no-show rates or high late-cancellation rates, policies such as overbooking (i.e., scheduling more appointments than provider capacity in each clinic session) and accepting walkin patients are often adopted to improve provider utilization and clinic accessibility. In the literature, many studies propose quantitative models to analyze or optimize overbooking policies (Kopach et al, 2007;Lawrence, 2007, 2012;Muthuraman and Lawley, 2008;Kros et al, 2009;Zeng et al, 2010;Ratcliffe et al, 2012), and also several studies investigate the appointment scheduling systems in the clinics accepting walk-in patients (Cayirli et al, 2006(Cayirli et al, , 2008(Cayirli et al, , 2012Kim and Giachetti, 2006;LaGanga and Lawrence, 2008). In the literature studies considering walk-in patients, it is assumed that a clinic accepts all walk-in patients, and that the cost structure for walk-in patients is same as that for patients with appointments scheduled.…”