Query languages for statistical databases

Statistical database management systems keep raw, elementary and/or aggregated data and include query languages with facilities to calculate various statistics from this data. In this article we examine statistical database query languages with respect to the criteria identified and taxonomy developed in Ozsoyoglu and Ozsoyoglu (1985b). The criteria include statistical metadata and objects, aggregation features and interface to statistical packages. The taxonomy of statistical database query languages classifies them with respect to the data model used, the type of user interface and method of implementation. Temporal databases are rich sources of data for statistical analysis. Aggregation features of temporal query languages, as well as the issues in calculating aggregates from temporal data, are also examined.     

Grouping Tests for Misspecification: An Application to Housing Demand

We consider several grouping tests for regression misspecification, with reference to housing-demand function estimation. We compare three existing test procedures, demonstrate modifications necessary in most applications, and propose a fourth test to distinguish between two categories of potential specification error. The test procedures are evaluated in artificial simulations of alternative errors. Finally, we apply the tests to FHA home purchase data. We reject the hypothesis that household and grouped regressions differ only by sampling error or random mismeasurement of household income or price. Our results have implications for choices among test procedures and interpretations of previous housing-demand analysis.     

Testing the homogeneous marginal utility of income assumption

We develop a test for the hypothesis that every agent from a population of heterogeneous consumers has the same marginal utility of income function. This homogeneous marginal utility of income (HMUI) assumption is often (implicitly) used in applied demand studies because it has nice aggregation properties and facilitates welfare analysis. If the HMUI assumption holds, we can also identify the common marginal utility of income function. We apply our results using a U.S. cross sectional dataset on food consumption.     

The Aggregation of Expert Judgment: Do Good Things Come to Those Who Weight?

Good policy making should be based on available scientific knowledge. Sometimes this knowledge is well established through research, but often scientists must simply express their judgment, and this is particularly so in risk scenarios that are characterized by high levels of uncertainty. Usually in such cases, the opinions of several experts will be sought in order to pool knowledge and reduce error, raising the question of whether individual expert judgments should be given different weights. We argue—against the commonly advocated “classical method”—that no significant benefits are likely to accrue from unequal weighting in mathematical aggregation. Our argument hinges on the difficulty of constructing reliable and valid measures of substantive expertise upon which to base weights. Practical problems associated with attempts to evaluate experts are also addressed. While our discussion focuses on one specific weighting scheme that is currently gaining in popularity for expert knowledge elicitation, our general thesis applies to externally imposed unequal weighting schemes more generally.     

《都柏林人》童年篇与通过仪式

詹姆斯·乔伊斯本人把《都柏林人》看作是为爱尔兰写的一部"精神史",试图"通过童年、青年、成年以及社会生活这样一个顺序来全方位地展示爱尔兰社会的精神症结"。正是以乔伊斯的这一言论为基点,国内外学者从现代主义角度、精神瘫痪或顿悟、女性角度、宗教、社会背景、美学、文体风格或叙述艺术等多个不同的角度对这部小说中的一篇或几篇进行解读和研究,为全面理解这部作品提供了丰富多样的研究方法。尝试利用社会人类学的通过仪式理论对其童年篇进行一个全新的解析,旨在指出童年篇对整部系列小说行文结构及主旨的决定性作用。     

Memory properties and aggregation of spatial autoregressive models

A random field displays long (resp. short) memory when its covariance function is absolutely non-summable (resp. summable), or alternatively when its spectral density (spectrum) is unbounded (resp. bounded) at some frequencies. Drawing on the spectrum approach, this paper characterizes both short and long memory features in the spatial autoregressive model. The data generating process is presented as a sequence of spatial autoregressive micro-relationships. The study elaborates the exact conditions under which short and long memories emerge for micro-relationships and for the aggregated field as well. To study the spectrum of the aggregated field, we develop a new general concept referred to as the ‘root order of a function’. This concept might be usefully applied in studying the convergence of some special integrals. We illustrate our findings with simulation experiments and an empirical application based on Gross Domestic Product data for 100 countries spanning over 1960–2004.     

Aggregation theorems and multidimensional stochastic choice models

In many choice situations, the options are multidimensional. Numerous probabilistic models have been developed for such choices between multidimensional options and for the parallel choices determined by one or more components of such options. In this paper, it is assumed that a functional relation exists between the choice probabilities over the multidimensional options and the choice probabilities over the associated component unidimensional options. It is shown that if that function satisfies a marginalization property then it is essentially an arithmetic mean, and if the function satisfies a likelihood independence property then it is a weighted geometric mean. The results are related to those on the combination of expert opinion, and various probabilistic models in the choice literature are shown to have the geometric mean form.     

Norovirus Dose–Response: Are Currently Available Data Informative Enough to Determine How Susceptible Humans Are to Infection from a Single Virus?

Two forms of single‐hit infection dose‐response models have previously been developed to assess available data from human feeding trials and estimate the norovirus dose‐response relationship. The mechanistic interpretations of these models include strong assumptions that warrant reconsideration: the first study includes an implicit assumption that there is no immunity to Norwalk virus among the specific study population, while the recent second study includes assumptions that such immunity could exist and that the nonimmune have no defensive barriers to prevent infection from exposure to just one virus. Both models addressed unmeasured virus aggregation in administered doses. In this work, the available data are reanalyzed using a generalization of the first model to explore these previous assumptions. It was hypothesized that concurrent estimation of an unmeasured degree of virus aggregation and important dose‐response parameters could lead to structural nonidentifiability of the model (i.e., that a diverse range of alternative mechanistic interpretations yield the same optimal fit), and this is demonstrated using the profile likelihood approach and by algebraic proof. It is also demonstrated that omission of an immunity parameter can artificially inflate the estimated degree of aggregation and falsely suggest high susceptibility among the nonimmune. The currently available data support the assumption of immunity within the specific study population, but provide only weak information about the degree of aggregation and susceptibility among the nonimmune. The probability of infection at low and moderate doses may be much lower than previously asserted, but more data from strategically designed dose‐response experiments are needed to provide adequate information.     

Parasitoid-mediated effects: apparent competition and the persistence of host–parasitoid assemblages

Indirect effects such as apparent competition (in which two hosts that do not compete for resources interact via a shared natural enemy) are increasingly being shown to be prevalent in the structure and function of ecological assemblages. Here, we review the empirical and theoretical evidence for these enemy-mediated effects in host–parasitoid assemblages. We first address questions about the design of experiments to test for apparent competition. Second, we consider factors likely to affect the coexistence of host species that share a parasitoid and are involved in apparent competition. We show that parasitoid aggregation, and the switching effect that this can generate when hosts occur in separate patches, not only promotes persistence but is also strongly stabilizing. The broader consequences of these effects are discussed. Received: November 6, 1998 / Accepted: January 13, 1999     

Group decision making on water resources based on analysis of individual rankings

In problems to do with managing water resources multiple decision makers are involved, each acting in their own right and using different value systems. In the literature on management science, several procedures are proposed in order to establish a collective preference based on the aggregation of different individual preferences. However, the well-known methods that focus on a single winner have some inconveniences that should be addressed. This paper is focused on a group decision making procedure based on the analysis of individual rankings with the aim of choosing an appropriate alternative for a water resources problem. This alternative is found to be the best compromise from the points of view of all actors involved in the decision problem. The structure of the method is set out as is its application to the water resources problem. A comparison with other methods is presented and discussed.