How do programs manage large pools of applicants?

One way to manage a large applicant pool is to hold a lottery. Programs will often publish an application to collect limited information to screen out obviously in-eligible applicants, and then hold a lottery to sort those applicants before they ask for detailed information and begin a thorough screening process. This reduces the screening burden on staff while at the same time reduces the amount of work applicants need to do if they are not going to be considered for a unit in the end because of a lack of availability.