Admissions to the Yale School of Public Health is extremely competitive and class sizes are the smallest among top-tier graduate public health programs around the country. Total enrollment in 2008 was 246 students (65 male, 181 female), with 98% maintaining full-time status. The incoming MPH class of 2009 consisted of 125 students (36% male, 64% female, 15% students of color, and 18% international), and represented 88 schools and 31 states. The incoming MPH class of 2018 consisted of 155 students (34% male, 66% female, 14% diversity population, and 26% international), and represented 95 schools and 39 states. YSPH does not report average GPA or GRE scores of incoming students, though unofficial reports report an average admitted GPA of 3.85 out of 4.00, making it one of the most selective public health schools in the nation. The Yale School of Public Health offers a number of specialty certificates in addition to students' departmental studies in a number of interdisciplinary concentrations, tracks and programs. Programs are offered in: Global Health, Public Health Modeling, and the Regulatory Affairs Track. The Climate Change and Health Initiative offers interdisciplinary resources to students and faculty from across the University. All courses taken outside of YSPH must be graded (H, HP, P) in order to receive a course unit. Students are allowed to enroll in courses in other Yale schools if there is space available and if the instructor agrees. Courses taken at Yale College (undergraduate) must typically be at the 300-series level or above in order to receive a course unit toward the M.P.H. degree. Some 200-series courses at Yale College may count if approved by the student's faculty adviser. The YSPH grading system is designed to foster an atmosphere of cooperative learning. Consequently, YSPH does not compute the grade point average (GPA) or class rank of its students. Students are graded only to provide them with a formal evaluation of their understanding of the concepts presented in their courses. The Internship, seminars, and colloquia receive a grade of Satisfactory (S) upon successful completion. The grade of “Q” indicates courses for which a student has received a course exemption. A grade of Honors should be assigned for performance that is distinguished. This reflects contributions that go beyond the requirements for the course, either in terms of the creativity of their application, the complexity of the settings in which the ideas are applied, or their ability to build on the methods and ideas taught in the class.