Every university follows some set rules for the induction of students in their course no matter they focus a degree program or a diploma or certificate. The number of seats in every class is limited, so it is not possible to entertain every applicant. So universities set their criteria for admissions.
Every university or even every educational institution over matric class admission follows a merit system for admission. The merit may either be consisted of only academic score or be a mix of it with entrytest score and interview. At university level merit calculation is made by evaluation test and academic performance by allying some weight of each.