Dynamic reliability models with conditional proportional hazards

A dynamic approach to the stochastic modelling of reliability systems is further explored. This modelling approach is particularly appropriate for load-sharing, software reliability, and multivariate failure-time models, where component failure characteristics are affected by their degree of use, amount of load, or extent of stresses experienced. This approach incorporates the intuitive notion that when a set of components in a coherent system fail at a certain time, there is a jump from one structure function to another which governs the residual lifetimes of the remaining functioning components, and since the component lifetimes are intrinsically affected by the structure function which they constitute, then at such a failure time there should also be a jump in the stochastic structure of the lifetimes of the remaining components. For such dynamically-modelled systems, the stochastic characteristics of their jump times are studied. These properties of the jump times allow us to obtain the properties of the lifetime of the system. In particular, for a Markov dynamic model, specific expressions for the exact distribution functions of the jump times are obtained for a general coherent system, a parallel system, and a series-parallel system. We derive a new family of distribution functions which describes the distributions of the jump times for a dynamically-modelled system.     

Internal Migration in Spain: Dealing with Multilateral Resistance and Nonlinearites

This article investigates the determinants of internal mobility of both foreigners and natives across Spanish provinces over the decade 2004‐14. Building on an extended gravity model, our econometric strategy controls for multilateral resistance to migration by including different fixed effects structures. Additionally, the article allows for some nonlinearities in the key economic determinants of migration, wages and unemployment. The main finding is that the impact of economic factors on internal migration is higher for foreigners than for natives; furthermore, the effect of these factors on internal migration is clearly nonlinear for the group of natives, while this only happens for foreigners when dyadic fixed effects of origin‐destination are considered. Finally, the article shows that the nature of the amenities with the greatest impact on internal movements differs between the two groups: foreigners look for social services and cultural amenities, whereas natives are more attracted by good climate conditions.     

Fundamental accrued capital gains and the measurement of top incomes: an application to Chile

Most previous studies of income inequality have either ignored capital gains or have used taxable realized capital gains to estimate top incomes. Neither of these approaches is fully satisfactory. We apply for the first time a new methodology that allows us to account for fundamental accrued capital gains as part of the top incomes in a theoretically consistent manner. We estimate the shares of the super-rich in Chile showing that accrued capital gains have a large impact on these estimates. Also, the top income shares estimated using fundamental capital gains appear to exhibit a more stable and presumably more plausible time profile than estimates based on capital gains derived from asset market variations.     

Rational-experiential thinking style and rational intergroup cooperation: the moderating role of intergroup conflict / Estilos de pensamiento racional-experiencial y la cooperación intergrupal racional: el rol modulador del conflicto intergrupal

Cooperative relationships between groups are difficult because of the high human capability to differentiate between in-group vs. out-group members. This obstacle exists even when the groups can obtain benefits for themselves from cooperation with other groups (rational cooperation). Based on an interactionist approach, the authors propose that personal (individual differences) and situational (conflicts) factors contribute to rational intergroup cooperation. The authors conducted a preliminary correlational study (Study 1) and an experimental investigation (Study 2). In Study 1, the authors examined, with 105 participants, the psychometric properties of the Spanish version of the Rational–Experiential Inventory (REI), measuring individual differences in information processing. In Study 2, the authors conducted an experimental investigation with 141 participants, testing the role of individual differences and conflict in intergroup rational cooperation. Findings of Study 1 showed that the scale has adequate psychometric properties. Results of Study 2 confirmed that the existence of both manipulated and perceived intergroup conflict reduces the magnitudes of the relationships between rational ability and rational cooperation. In addition, perceived intergroup conflict increased the magnitude of the links from experiential ability and experimental engagement to rational cooperation. Both individual differences and previous conflict have a role in predicting rational intergroup cooperation. According to the interactionist approach, personal and situational factors should be considered in the understanding of intergroup relationships.     

Aggregating Political Dimensions: Of the Feasibility of Political Indicators

Political indicators are widely used in academic writing and decision making, but remain controversial. This paper discusses the problems related to the aggregation functions they use. Almost always, political indicators are aggregated by weighted averages or summations. The use of such functions is based on untenable assumptions (existence of homogeneous substitution rates, total compensation, and strict monotonicity). We show through concrete examples how these hidden assumptions are likely to produce results that are basically an artifact of ad hoc decisions, which additionally contradict very fundamental notions common to all credible political theories. We suggest, also through example, that some—necessarily partial—solutions are possible.     

Robust Methods of Building Regression Models—An Application to thè Housing Sector

This article studies robustification strategies for the linear model in the presence of outliers. The advantages of an internal analysis of the robustness of least squares for a given sample are pointed out. The application of this methodology is illustrated by building an explicit model of the determinants of rental housing values in the Madrid Metropolitan Area.     

Materialism in Pedagogy Students in Chile

Many studies have used Richins and Dawson’s (J Consum Res 19: 303–316, 1992) Material Values Scale (MVS), applying it to different types of populations that exhibit a particular psychometric behavior, and showing little stability in their factorial structure. In the present study, 1,070 pedagogy students from the northern, central and southern regions of Chile answered the MVS. This sample was randomly divided in two. Using the first sub-sample (N = 539), an exploratory factorial analysis was carried out, from which a structure of nine items was grouped into two factors called “Social Success” and “Personal Happiness”, which presented adequate reliability. Later, with the second sub-sample (N = 531), the factorial structure indicated above was put to the test through a confirmatory factorial analysis. The data from the model show that the scale contains 8 items in total, grouped into two dimensions. The factorial loads are significant at the level of 1 %, which indicates that the 2-factor structure can be confirmed. Finally—using the proposed structure—the presence of the students’ material values was evaluated.     

To What Extent Did Ethnicity and Economic Issues Matter in the 2007 Disputed Kenyan Elections?

This article assesses the key factors that influenced the intention to vote in the 2007 presidential election in Kenya, using data from a survey and other external datasets. Ethnicity was found to be one of the main factors. However, access to private and public goods, poverty and differences in wealth across ethnic groups also mattered, depending on how the voter claimed to be self‐identified. Those who self‐identified in terms of their ethnicity were influenced the most by access to services such as schools, health clinics and police stations, evidence suggesting that voters use ethnicity as a proxy to gauge which candidates will give them greater access to services provided by the state.     

Size does matter: Passive sampling in urban parks of a regional bat assemblage

Urban Ecosystems - We studied the occurrence of bats in urban parks in the city of Madrid (Spain), and the resulting patterns were compared with bat occurrence in the surrounding region. In this...