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71.
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In this fundamental draft we shall introduce the concept of social propositional spaces as a general notion of social science and in particular language, logic and methodology. This should help us bridge an old gap between extension and cognition, or said in more specific words, between space as conceived in mathematics or physics and space as is brought in by social location, by the meaning of predicates, their explanation and logic. 1 We shall not rely on the idea of factor analysis where some “main components” are fit into the data. Because the notion of euclidean normalization and orthogonality, in this context, is a bit artificial. We first show how combinatorial manifolds of statements can be represented in finite vector spaces over the Galois field F2. This space which we denote as logic statement space can be spanned by generators of alternating codes. In this way the old concepts of truth tables and interaction attributes can be linked to informatics and in particular code theory and geometry. Extending the logic statement space onto a real vector space by mapping units of the finite rings onto units of the real rings we obtain logistic statement spaces. It turns out that vectors in logistic statement spaces represent cross-tables of logits connected with logistic regression analysis. As a completion of the theory we show that the logit is the first derivative of entropy with respect to probability.  相似文献   
73.
Some employers have begun to undertake a variety of initiatives, collectively termed value-based purchasing (VBP), which aim at factoring quality into the purchasing decision-making process when negotiating costs with providers and insurers. There is evidence that the VBP movement has begun gaining momentum; yet it is unclear whether employers are firmly committed to VBP principles. By surveying a national sample of employers, this study investigates the extent to which employers are currently engaged in VBP activities and also increases our understanding of barriers hampering the broader implementation of these activities.  相似文献   
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Product differentiation and competitive pressure   总被引:1,自引:1,他引:0  
This paper compares the commonly used linear demand model introduced by Bowley (The mathematical groundwork of economics, Oxford University Press, Oxford, 1924) with the specification of Shapley and Shubik (Kyklos 22:30?C44, 1969). The latter has the advantage that aggregate demand does not depend on a parameter that measures the degree of product differentiation. This allows to interpret variations in the degree of product differentiation as changes in competitive pressure because these changes can influence aggregate demand only through changes in equilibrium prices and quantities. The consequences of the alternative specifications are made explicit with two applications. In both cases the different specifications yield substantial changes in important results in industrial economics.  相似文献   
76.
In search engine marketing, such as on Google, advertisements' ranking and prices paid per click result from generalized, second-price, sealed bid auctions that weight the submitted bids for each keyword by the quality of an advertisement. Conventional wisdom suggests that advertisers can only benefit from improving their advertisement's quality. With an empirical study, this article shows that quality improvements have complex effects whose returns are actually unclear: 5% of all quality improvements to an advertisement lead to higher prices (measured by price per click) per keyword, 100% to a higher number of clicks, 53% to higher costs for search engine marketing, and 37% to lower profits. Quality improvements lead to higher weighted bids, which only lower prices if they do not improve the ranking of the advertisement. Otherwise, better ranks likely lead to higher prices. A decomposition method can disentangle these effects and explain their effects on search engine marketing costs and profits. Finally, the results indicate that advertisers benefit if they lower their bids after improvements to advertising quality.  相似文献   
77.
We argue that the use of publicly available and easily accessible information on economic and financial crises to detect structural breaks in the link between stock returns and macroeconomic predictor variables improves the performance of simple trading rules in real time. In particular, our results suggest that accounting for structural breaks and regime shifts in forecasting regressions caused by economic and financial crises has the potential to increase the out-of-sample predictability of stock returns, the performance of simple trading rules, and the market-timing ability of an investor trading in the U.S. stock market.  相似文献   
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Highly disconcerting at the time, in retrospective, the 2009 H1N1 influenza pandemic looks like much ado about nothing. As a consequence, many accused the media of having created an artificial hype or hysteria around the new virus, thus contributing to unwarranted public fear. The current paper set out to examine the validity of such accusations. We integrated empirical findings on whether the media dramatized H1N1 on a global scale through systematically reviewing prior content-analytic studies. We developed a coding scheme specifying three indicators of dramatized media coverage that – together – inform about how mass media coverage about H1N1 may amplify risk perceptions in the public: (a) the volume of media coverage, (b) the media content presented, particularly an overemphasis of threat while neglecting measures of self-protection and (c) the tone of coverage. Results show that media attention was immense, that news content stressed threat over precautionary measures, while the pattern of coverage tonality remained nebulous due to conflicting findings. The present review also revealed a critical gap in existing knowledge about the tone of media coverage on H1N1, and discusses implications for future research on dramatization of public health risks by the media.  相似文献   
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