This makes it seem as if ex-smokers are more likely to die of emphysema or lung cancer than current smokers. It is interesting to note that when lifelong smokers are told they have lung cancer or emphysema, many of them quit smoking. Is it possible that having lung cancer causes one to smoke?.Is there a strong association between smoking and subsequent occurrence of lung cancer?.Does exposure to tobacco smoke and air pollution precede the occurrence of lung cancer?.Guided by this principle, we endeavored to determine whether ubiquitous age-related deficits in associative memory. In accord with the specificity principle of memory, these declines may occur because associative memory requires retrieval of specific information. Thirty-six college females were randomly assigned to either an experimental or a control group and both groups received 54 practice trials on a ladder climb task over four consecutive days (3,18. The ability to remember associations among components of an event, which is central to episodic memory, declines with normal aging. To conclude that lack of exercise is a cause of heart disease, one needs to review the body of evidence suggesting a causal relationship and also consider other criteria. The purpose of the present study was to test the specificity of training principle from exercise physiology in the context of motor skill acquisition. Efficacy is the invivo potency the maximum response achieved from a drug (1-3,5).The interaction (e.g. A cause must be associated with the outcome, but simply demonstrating an association is not enough. Potency describes the relationship between the drug dose and the magnitude of the effect (1-5).High potency induces a strong effect with a low drug dose. Causative factors can also be the absence of a preventive exposure, such as not wearing a seatbelt or not exercising. It can be the presence of an adverse exposure, e.g., increased risks from working in a coal mine, using illicit drugs, or breathing in second hand smoke. It has been convincingly demonstrated that people of lower socioeconomic status (SES) have a higher risk of lung cancer, i.e., there is a clear association, but does that mean that low SES is a cause of lung cancer? A more plausible explanation is that people of lower SES are more likely to smoke and to be chronically exposed to air pollution and that exposure of the respiratory tract to these contaminants causes mutations in bronchial cells that can eventually produce a cancer.Ĭausation: Causation means that the exposure produces the effect. However, one's religion is not a cause of breast cancer. Jewish women have a higher risk of breast cancer, while Mormons have a lower risk. However, there is obviously no causal relationship. For example, there is a statistical association between the number of people who drowned by falling into a pool and the number of films Nicolas Cage appeared in in a given year. Two variables may be associated without a causal relationship. Epidemiologists ultimately want to be able to draw conclusions about causation, but most epidemiologic studies focus on establishing associations.Īssociation: Is a specified health outcome more likely in people with a particular "exposure"? Is there a link? Association is a statistical relationship between two variables. When considering the relationship between exposures and health outcomes, it is important to distinguish between association and causation.
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