Parallel sequential Monte Carlo for stochastic gradient-free nonconvex optimization

Statistics and Computing - We introduce and analyze a parallel sequential Monte Carlo methodology for the numerical solution of optimization problems that involve the minimization of a cost...     

Complements or substitutes? The contingent role of corporate reputation on the interplay between internal R&D and external knowledge sourcing

Existing research does not provide a clear answer to the question of whether internal knowledge development and external knowledge sourcing are complementary or substitutive innovation activities. This paper adopts a contingent approach for addressing this issue by examining whether and how the interactive effect of internal R&D efforts and external knowledge sourcing on product innovation performance may be affected by the firm’s corporate reputation. In doing so, a three-way interaction model is applied to a sample of 251 Spanish high-technology manufacturing firms. Interestingly, initial results support the substitutive argument: the positive effect of internal R&D on product innovation performance diminishes as the exposure to external knowledge increases. However, in well reputed companies, interaction becomes positive, revealing a complementary effect. Thus, the study extends the traditional approach focused on determining whether internal and external knowledge sourcing are complements or substitutes by showing that their interplay depends on other firm-specific characteristics. Moreover, identifying corporate reputation as a source of complementarity between both activities provides an additional explanation of how corporate reputation contributes to a more effective management of knowledge assets.     

Weighted quantile regression with nonelliptically structured covariates

Although quantile regression estimators are robust against low leverage observations with atypically large responses (Koenker & Bassett 1978), they can be seriously affected by a few points that deviate from the majority of the sample covariates. This problem can be alleviated by downweighting observations with high leverage. Unfortunately, when the covariates are not elliptically distributed, Mahalanobis distances may not be able to correctly identify atypical points. In this paper the authors discuss the use of weights based on a new leverage measure constructed using Rosenblatt's multivariate transformation which is able to reflect nonelliptical structures in the covariate space. The resulting weighted estimators are consistent, asymptotically normal, and have a bounded influence function. In addition, the authors also discuss a selection criterion for choosing the downweighting scheme. They illustrate their approach with child growth data from Finland. Finally, their simulation studies suggest that this methodology has good finite‐sample properties.     

An AHP-based evaluation procedure for Innovative Educational Projects: A face-to-face vs. computer-mediated case study

In this paper a procedure to evaluate proposals for Educational Innovation Projects is proposed. This methodology should help the Institute of Educational Sciences of the Politechnical University of Valencia to choose the best Educational Project, the final aim being to provide the Administration with a stringent evaluation methodology, since the current evaluation methodology was found to be neither sufficiently objective nor systematic.     

Multimarket pioneers: Does multimarket contact improve their performance?

First-mover advantages (FMA) and multimarket contact (MMC) have evolved independently in the strategic management literature. This is surprising because FMA erode as a result of competition which, in turn, is affected by MMC. This paper links these literatures through the concept of spheres of influence and analyses the effect of MMC on pioneers' profitability. We use the order of market entry to identify spheres of influence and to determine their distribution among multimarket firms. The distribution of spheres of influence allows us to distinguish between reciprocal MMC and non-reciprocal MMC and to study how each of them determines pioneers' profitability. We test our hypotheses in the mobile telecommunications industry. Our findings show that reciprocal MMC has a positive effect on pioneers’ results, but non-reciprocal MMC negatively affects them.     

Old-age Pensions in Spain: Recent Reforms and Some of Their Consequences for the Risk of Poverty

The starting point of this study is based on the supposition that the successive reforms carried out on the Spanish system of old‐age pensions since the 1980s have altered both the intergenerational distribution of income and the risk of poverty for the elderly. The article will first outline how demographic factors and personal incomes affect the risk of poverty among the elderly. The second part focuses attention on the mediating role played by the social security system in the distribution of intergenerational income, and underlines how the adoption of a longitudinal viewpoint of the intergenerational positions helps us to understand the development of the risk of poverty among the elderly. The third part describes in brief the successive reforms that were carried out on the Spanish regime of retirement pensions. Finally, an analysis of the evolution of the personal incomes of the elderly and younger generations has been made, based on the data collected by the European Community Household Panel from 1994 to 2001. This analysis suggests that the reforms have increased the risk of poverty among the over‐60s owing to a combination of two factors. On the one hand, there has been an increasing tendency among the over‐60s to stop working completely, which has reduced job earnings especially for men aged between 60 and 70. Even more important has been the failure of public pensions to keep pace with the increase in the standard of living, though it is true that they have helped maintain the average purchasing power of the less well‐off old‐age pensioners.     

Changes in Objective and Self-Reported Measures of Physical Capacity After an Intervention in Obese Older Women

The aim of this study was to determine if objective and self-reported measures of physical capacity are two equivalent methods to detect changes following an intervention in obese older women. 36 obese women aged between 55 and 75 years participated in a 3-month study with the aim of improving physical capacity by caloric restriction and/or resistance training. Physical capacity was measured objectively with 10 different tests and self-reported with the SF-36 physical functioning score (SF-36 PF score). Then the performance-to-objective tests were computed using quartiles to provide a baseline global physical capacity score. The mean percentage of change of the 10 tests as well as the SF-36 PF score were also calculated after the study. Body composition was measured by dual-energy X-ray (DXA) absorptiometry. The baseline global physical capacity score and the SF-36 PF score were significantly correlated at baseline (r = 0.43; P < 0.01). Eight out of the 10 objective tests of physical capacity improved after the intervention, while no improvement was observed for the SF-36 PF score. On average, percentage of change in physical capacity was 4.1 ± 5.9% for the SF-36 PF score and 11.1 ± 2.9% for the objective measures. However, no significant correlation was observed between percentage of changes between the two approaches after the intervention (r = 0.32; P = 0.07). Based on these results, the method used to quantify physical capacity after an intervention may have major implications on the outcomes. The methods used should be carefully analyzed in regard to the objective of the study.     

Women's Alternative Internet Radio and Feminist Interactive Communications

The nude male centrefold spread like a virus through the new women's magazines of the seventies. At the time, and since, the academic gaze has viewed the centrefold as little more than a joke, a failure for feminism and female sexuality. This article returns to the heyday of the centrefold and listens to the responses of ordinary women in reader letters published in the new Australian women's magazine Cleo from 1972 until 1985. It argues that far from being a failure, these representations of the nude male became a practice of popular feminism, one of the early representations of popular feminist desire in mainstream women's magazines.     

Patterns of Racial Socialization and Psychological Adjustment: Can Parental Communications About Race Reduce the Impact of Racial Discrimination?

This study uses two waves of data to examine the relations among racial discrimination experiences, patterns of racial socialization practices, and psychological adjustment in a sample of 361 African American adolescents. Using latent class analyses, we identified four patterns of child‐reported racial socialization experiences: Moderate Positive, High Positive, Low Frequency, and Moderate Negative. Experiencing racial discrimination was associated with higher levels of depressive symptoms, more perceived stress, and lower levels of well‐being. On average, adolescents who experienced High Positive patterns of racial socialization reported the most positive psychological adjustment outcomes, while adolescents in the Low Frequency and Moderate Negative clusters reported the least favorable outcomes. Results suggest that High Positive racial socialization buffers the negative effects of racial discrimination on adolescents' perceived stress and problem behaviors. Together, the findings suggest that various patterns of racial socialization practices serve as risk, compensatory, and protective factors in African American adolescent psychological adjustment.