On explanation Aristotelean and Hempelean

Given the great historical distance between scientific explanation as Aristotle and Hempel saw it, some important similarities and differences between the two approaches are examined and appraised, especially the inclination to take deduction itself as the very model of scientific knowledge: an inclination we have good reasons to reject.     

Modelling Variability in the Branching Structure of Strawberry Inflorescences

The branching structure of inflorescences of the cultivated strawberry ( Fragaria × ananassa Duch.) is very variable. This paper demonstrates that some aspects of this variability are well described by a simple stochastic model of branching that has two adjustable parameters. The model is shown to provide a good fit to data from a set of almost 700 inflorescences of the cultivar Elsanta, collected over two successive years. For one parameter the maximum likelihood estimator is a moment estimator which is fully efficient even if the detailed branching structure of the inflorescences is not recorded. This parameter provides a convenient summary of branching vigour. The maximum likelihood estimator of the second parameter must be determined iteratively and can be quite inefficient unless the full branching structure is recorded. The model demonstrates that branching structure is affected by the order in which inflorescences emerge on the plant.     

Weighted Approximations to Continuous Time Martingales with Applications

A weighted approximation to a sequence of continuous time martingales by a time transformed Wiener process is established. The basic tool of proof is the Skorohod imbedding for martingale difference sequences. As an application of the main result a useful weighted approximation to the randomly weighted uniform empirical process is derived. A number of other applications are also discussed.     

A Match Made in Heaven? Career Development Theories and the School-to-Work Transition

This article discusses the major contributions (Krumboltz & Worthington, 1999; Lent, Hackett, & Brown, 1999; Savickas, 1999; Swanson & Fouad, 1999) to this special issue of The Career Development Quarterly on the application of career development theories to the school-to-work transition. Common thematic elements in these 4 articles include a focus on the individual who faces the transition from high school to work and an emphasis on the developmental aspects of the transition. The article concludes with a cautionary recommendation that theory-building efforts derived from the individual experiences of work-bound youth ought to be included in theoretical and intervention initiatives to facilitate the school-to-work transition.     

Segregation and Mortality: The Deadly Effects of Racism?

Elevated rates of mortality for African Americans compared to whites, coupled with the persistence of high levels of racial residential segregation, have directed attention to the structural manifestations of racism as potentially important pathogens for health. Using national mortality and census data for 1990 and a measure of black social isolation from whites, we examine the association between residential segregation and mortality in 107 major U.S. cities. Our analyses revealed that black social isolation tended to predict higher rates of mortality for African American males and females, although the strength of the association varied by cause of death. Socioeconomic deprivation explained a modest part of this association for black males but not for black females. Our analyses also found that a positive association between social isolation and mortality was more pronounced, for both blacks and whites, in cities that were also high on the index of dissimilarity. These findings highlight the need for research to identify the specific mechanisms and processes that link residential environments to adverse changes in health status.     

Developing social work education in Lithuania

From 1991 through 1998, during the turmoil of independence and transition to a democracy and free-market economy, the authors established the first social work education programme in Lithuania and assisted Lithuanian professionals to assume responsibility for the programme. This article supplies an initial general and conceptual narrative and analyses some of the factors that influenced the development of the programme and a practice model to address conditions in Lithuania.     

Globalization, the structure of the world economy and economic development

How does the structure of the world economy determine the gains from participation therein? In order to answer this question, we conduct a state of the art network analysis of international trade to map the structure of the international division of labor (IDL). We regress cross-national variation in economic growth on positional variation and mobility of countries within the IDL from 1965 to 2000. We find that the highest rates of economic growth occurred to countries in the middle of the IDL over the course of globalization. Second, we find that upper tier positions in the IDL are converging with each other, but diverging from the lower tier. This suggests that the mechanism underlying the rapid economic growth in intermediate positions was their uniquely high rates of upward mobility, in turn a function of their middling position. Taken together, these findings suggest that a country’s long-term economic development is conditioned by its position in the IDL.     

Reexamining the ethnic hierarchy of locational attainment: Evidence from Los Angeles

Because of a lack of data, the locational attainment literature has not incorporated documentation status into models examining group differences in neighborhood quality. I fill this void by using the Los Angeles Family and Neighborhood Survey, which permits the identification of undocumented respondents, allowing a reexamination of the ethnic structure of locational attainment in this important immigrant-receiving city. Results first suggest that while undocumented Latinos live in the poorest quality communities, blacks live in neighborhoods that are similar to native-born Latinos and better than foreign-born Asians and Latinos. Second, the effects of education are strongest for blacks, allowing the highly educated an opportunity to reside in communities that are of better quality than educated Latinos and Asians. Thus, undocumented Latinos replace blacks at the bottom of the locational attainment hierarchy, allowing educated blacks in Los Angeles to reside in better neighborhoods than blacks in the nation at large.     

Does Market Incompleteness Matter?

This paper argues that incompleteness of intertemporal financial markets has little effect (on welfare, prices, or consumption) in an economy with a single consumption good, provided that traders are long–lived and patient, a riskless bond is traded, shocks are transitory, and there is no aggregate risk. In an economy with aggregate risk, a similar conclusion holds, provided traders share the same CRRA utility function and the right assets are traded. Examples demonstrate that these conclusions need not hold if the wrong assets are traded or if the economy has multiple consumption goods.     

Communicating uncertainty in national security intelligence: Expert and nonexpert interpretations of and preferences for verbal and numeric formats

Organizations in several domains including national security intelligence communicate judgments under uncertainty using verbal probabilities (e.g., likely) instead of numeric probabilities (e.g., 75% chance), despite research indicating that the former have variable meanings across individuals. In the intelligence domain, uncertainty is also communicated using terms such as low, moderate, or high to describe the analyst's confidence level. However, little research has examined how intelligence professionals interpret these terms and whether they prefer them to numeric uncertainty quantifiers. In two experiments (N = 481 and 624, respectively), uncertainty communication preferences of expert (n = 41 intelligence analysts in Experiment 1) and nonexpert intelligence consumers were elicited. We examined which format participants judged to be more informative and simpler to process. We further tested whether participants treated verbal probability and confidence terms as independent constructs and whether participants provided coherent numeric probability translations of verbal probabilities. Results showed that although most nonexperts favored the numeric format, experts were about equally split, and most participants in both samples regarded the numeric format as more informative. Experts and nonexperts consistently conflated probability and confidence. For instance, confidence intervals inferred from verbal confidence terms had a greater effect on the location of the estimate than the width of the estimate, contrary to normative expectation. Approximately one-fourth of experts and over one-half of nonexperts provided incoherent numeric probability translations for the terms likely and unlikely when the elicitation of best estimates and lower and upper bounds were briefly spaced by intervening tasks.