Causal importance

Various methods have been proposed to measure the importance of inputs (Sarle, 1998) and are likely to be useful in different applications of neural nets. The two most common notions of importance are predictive importance and causal importance. Predictive importance is concerned with the increase in generalization error when an input is omitted from a network. Causal importance is concerned with situations in which an individual wants to quantify the relationship between input value manipulation and consequent output change. 

I never before published this overly simple derivation of ui w), leaving it archived only in lab notebooks in anticipation that it would soon be superseded. That has still not happened, so I bring it out in this review as a potential test to distinguish between the opposed notions that the spinning wave only incidentally entails a relatively quiescent center of no causal importance (in which case it might work well), and that the spinning rotor emanates waves (in which case it might not.)... 

In the future, the preventive tole of toxicology will be emphasized. It will be increasingly important to develop early indicators to monitor longterm subtle exposures that predict deleterious effects that are known to have a causal relationship with occupational exposures. In addition to collection of blood and urine samples, also collection of cells from points of... 

Table 2 Most important faecal-orai water-borne infectious diseases with their causal agents...

Temporal Relationships of Adverse Events. The temporal relationship between duration of product exposure and development of an adverse event is important in assessing causality. But how can data on temporal relationships be systematically summarized in a database containing thousands or even hundreds of thousands of subjects Temporal relationships cannot be clearly elicited if only frequencies of adverse events between treatment and control groups are compared. There can be many disparities in the subjects time of exposure or time at risk. Toxic manifestations of drugs may not occur until several months or even years after the initial exposure to the drug. How do we systematically assess delayed toxicity of a previously prescribed drug from the effect of a newly prescribed drug Such a scenario occurred with reported cases of pancreatitis associated with valproic acid therapy, in which some cases appeared several years after therapy [2]. 

Haemophilus influenzae owes its specific name to the fact that it was thought to be the causal organism of influenza (now known to be a virus disease) as it was often isolated in cases ofinfluenza. It is the main cause ofinfantile meningitis and conjunctivitis and is one of the most important causes of chronic bronchitis. 

Sampling studies can be classified Into two types - enumeratlve, or descriptive, and analytic (j ). The classification Is Important because the applicable statistical methods and approaches are different for these two types. The objective of either type of study Is to provide a basis for action. In an enumeratlve study the action Is directed to the population from which the samples were taken. How or why the population was formed Is not of primary Interest. In an analytic study, the primary Interest Is the causal system or process which created the conditions observed In the study. Action taken Is directed toward this process rather than the population sampled. 

In addition to the classical stress hormones already reviewed, several other hormones are augmented in response to stress. Stress-induced prolactin release is one of the most frequently studied examples. There is no doubt about the causal relationship between stress and increased pituitary prolactin release, but the biological meaning is much less clear (G2). This phylogenetically old hormone has been shown to have more than 85 different functions in all vertebrate species. However, besides its role in the induction of maternal lactogenesis, the physiological importance of prolactin is at present not fully established. Experimental and clinical evidence supports the view that prolactin is also an immunoregulating hormone (M44, R18). Prolactin receptors are present on human T and B lymphocytes (R18), and T lymphocytes depend on prolactin for maintenance of immunocompetence (B19). In addition, it has been shown that prolactin is able to influence the devel-... 

However, what is it about social status and social integration that makes them so important to health One proposal is that social status indicates social capital, and that it is a person s social capital which is most important to health. Wilkinson rejects this hypothesis, stating that social capital is an epiphenomenon and that we still have to identify the causal factors underlying it (Wilkinson 1999, p. 52). 

On this view that emphasizes the importance of models, Lander s metaphor of modern genetics as summarizable in a -dimensional periodic chart involving many thousands of genes falls short. It does so because it does not recognize the temporal/causal processing dimension of molecular... 

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