Cancer Prevention Fellowship Program, Office of Preventive Oncology, National Cancer Institute, Bethesda, MD 20892-7105, USA. This article has been cited by other articles in PMC. Abstract. Causation is an essential concept in epidemiology, yet there is no single, clearly articulated definition for the discipline. From a systematic review of the literature, five categories can be delineated: production, necessary and sufficient, sufficient-component, counterfactual, and probabilistic.
Broad Valley. Broad Valley (63Â°22â²S 57Â°55â²W / 63.367Â°S 57.917Â°W / -63.367; -57.917Coordinates: 63Â°22â²S 57Â°55â²W / 63.367Â°S 57.917Â°W / -63.367; -57.917) is a descriptive name for the broad glacier-filled valley on the south side of Laclavere Plateau, Trinity Peninsula. The name was suggested by V.I.
Rift valleys are sometimes called grabens, which means âditchâ in German. While there is no official distinction between a graben and a rift valley, a graben usually describes a small rift valley. A rift valley is a lowland region that forms where Earthâs tectonic plates move apart, or rift.