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.
A valley formed by flowing water, or river valley, is usually V-shaped. The exact shape will depend on the characteristics of the stream flowing through it. Rivers with steep gradients, as in mountain ranges, produce steep walls and a bottom.Shallower slopes may produce broader and gentler valleys. valley in its broadest geographic sense is also known as a dale. A valley through which a river runs may also be referred to as a vale. A small, secluded, and often wooded valley is known as a dell or in Scotland as a glen.