Chiropractic colleges require a minimum of four to five academic years of professional resident study involving no less than 4000 hours. Professional study includes clinical experience under strict supervision by qualified faculty members in institutional clinics. A major part of chiropractic education is devoted to such basic science subjects as anatomy, biochemistry, microbiology, pathology, public health, diagnosis and treatment of patients. During this period, about half of the chiropractic student's time is spent in a clinic, examining and treating patients under close supervision.