TY - CHAP M1 - Book, Section TI - Chapter 8. Cohort Studies A1 - Greenberg, Raymond S. A1 - Daniels, Stephen R. A1 - Flanders, W. Dana A1 - Eley, John William A1 - Boring, John R. PY - 2005 T2 - Medical Epidemiology, 4e AB - Studies in which the investigator passively observes events without determining assignment of exposure are referred to as observational. Cohort studies are observational studies in which the investigator determines the exposure status of subjects and then follows them for subsequent outcomes. A prospective cohort study is one in which the exposure and subsequent outcome status of each subject is determined after the onset of the investigation. A retrospective cohort study is one which utilizes historical information on exposure status and subsequent outcome. The risk ratio or relative risk is a measure of association between the exposure and disease and is defined as the risk among the exposed divided by the risk among the unexposed. A risk ratio > 1 implies that exposure increases the risk of disease, whereas a risk ratio < 1 implies that exposure decreases the risk of disease. The attributable risk percentage is a measure of the proportion of the total risk among exposed persons that is related to their exposure. SN - PB - The McGraw-Hill Companies CY - New York, NY Y2 - 2024/03/28 UR - accesspharmacy.mhmedical.com/content.aspx?aid=545914 ER -