Early Word Segmentation by Infants and Toddlers With Williams Syndrome

This study tested the ability of English infants and toddlers with Williams syndrome to segment, that is, to extract from fluent speech, bisyllabic nouns that had either a strong–‐weak stress pattern (predominant in English), or a weak–‐strong stress pattern. The testing procedure was the same for both types of words: Children were familiarized with instances of isolated nouns, and then tested on their recognition of these nouns embedded in passages. In English, typically developing infants start segmenting strong–‐weak nouns by 7.5 months of age, and weak–‐strong nouns by 10.5 months. Our clinical population was able to segment strong–‐weak nouns, but failed, despite chronological ages above 15 months, to segment weak–‐strong words. These results suggest that the development of word segmentation is seriously delayed in Williams syndrome. This deficit in early phonological processing may contribute to a fuller understanding of the late lexical onset in this population, a phenomenon that had hitherto only been explained in terms of cognitive and semantic deficits.     

Factors That Influence Persistence in Science and Engineering Career Aspirations

The author investigated students' persistence regarding career aspirations in science and engineering (SE) professional careers as a function of race and sex. In a nationally representative sample of 8th graders, persistent racial minority and female students were compared with nonpersistent racial minority and male students regarding their self‐concept, parental involvement, socioeconomic status, and academic achievement. Men were more likely than women to persist in SE career aspirations. Persistent students scored higher than did nonpersistent students on all of the variables studied. Academic proficiency and math self‐efficacy were 2 of the strongest predictors of persistence in SE careers.     

A note on sample size savings with the use of a single well‐controlled clinical trial to support the efficacy of a new drug

In terms of the risk of making a Type I error in evaluating a null hypothesis of equality, requiring two independent confirmatory trials with two‐sided p‐values less than 0.05 is equivalent to requiring one confirmatory trial with two‐sided p‐value less than 0.001 25. Furthermore, the use of a single confirmatory trial is gaining acceptability, with discussion in both ICH E9 and a CPMP Points to Consider document. Given the growing acceptance of this approach, this note provides a formula for the sample size savings that are obtained with the single clinical trial approach depending on the levels of Type I and Type II errors chosen. For two replicate trials each powered at 90%, which corresponds to a single larger trial powered at 81%, an approximate 19% reduction in total sample size is achieved with the single trial approach. Alternatively, a single trial with the same sample size as the total sample size from two smaller trials will have much greater power. For example, in the case where two trials are each powered at 90% for two‐sided α=0.05 yielding an overall power of 81%, a single trial using two‐sided α=0.001 25 would have 91% power. Copyright © 2004 John Wiley & Sons, Ltd.     

A Further Examination of Cumulative Prospect Theory Parameterizations

Recent experimental studies have focused on fitting parameterized functional forms to cumulative prospect theory's weighting function. This paper examines the behavioral implications of the functional forms and the estimated parameters. We find that none of the parameterizations can simultaneously account for gambling on unlikely gains and the Allais paradox behavior or other strong choice patterns from experiments. Parameter estimates that lead to reasonable amounts of insurance and gambling behavior tend to also generate large risk premia. Taken as a whole, the analysis suggests that the functional forms proposed in the literature are not suitable for generalization to applied settings.     

Bayesian methods for generalized linear models with covariates missing at random

The authors propose methods for Bayesian inference for generalized linear models with missing covariate data. They specify a parametric distribution for the covariates that is written as a sequence of one‐dimensional conditional distributions. They propose an informative class of joint prior distributions for the regression coefficients and the parameters arising from the covariate distributions. They examine the properties of the proposed prior and resulting posterior distributions. They also present a Bayesian criterion for comparing various models, and a calibration is derived for it. A detailed simulation is conducted and two real data sets are examined to demonstrate the methodology.     

La falta de brazos

Sans résumé

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Normative population theory

Conclusion We have shown, contrary to the claims of Cowen, that average and critical-level utilitarianism, which do not suffer from the repugnant conclusion, do not recommend the killing of people with low but positive utilities. We have shown, in addition, that Methuselah's paradox and the repugnant conclusion do not stem from preferences that are represented by additive utility functions. Further, we have shown that Cowen's ideal participant method suffers from the repugnant conclusion.We believe that Parfit's [4] criticism of classical utilitarianism — that it satisfies the repugnant conclusion — should be taken seriously. That suggests that the ideal participant method should be rejected (along with classical utilitarianism) as a reasonable solution to the optimal population problem.We have benefited from private correspondence with T. Cowen, and the remarks of T. Hurka and an anonymous referee.     

Changes in Support From Confidants,Children, and Friends Following Widowhood

This paper examines the extent to which widowhood affects changes in (a) the availability of a confidant, (b) emotional support from children, and (c) emotional support from friends/relatives both 6 and 18 months after spousal loss. Analyses are based on data from the Changing Lives of Older Couples, a prospective study of 1,532 married individuals aged 65 and older. Compared to married persons, widowed persons are less likely to have a confidant, yet they receive greater support from children, friends, and relatives, controlling for support prior to widowhood. The findings suggest that, although close social relationships may remain stable in the course of normal aging, stressful events such as widowhood may bring forth both losses and gains in social support.