Marginal semiparametric multivariate accelerated failure time model with generalized estimating equations

The semiparametric accelerated failure time (AFT) model is not as widely used as the Cox relative risk model due to computational difficulties. Recent developments in least squares estimation and induced smoothing estimating equations for censored data provide promising tools to make the AFT models more attractive in practice. For multivariate AFT models, we propose a generalized estimating equations (GEE) approach, extending the GEE to censored data. The consistency of the regression coefficient estimator is robust to misspecification of working covariance, and the efficiency is higher when the working covariance structure is closer to the truth. The marginal error distributions and regression coefficients are allowed to be unique for each margin or partially shared across margins as needed. The initial estimator is a rank-based estimator with Gehan’s weight, but obtained from an induced smoothing approach with computational ease. The resulting estimator is consistent and asymptotically normal, with variance estimated through a multiplier resampling method. In a large scale simulation study, our estimator was up to three times as efficient as the estimateor that ignores the within-cluster dependence, especially when the within-cluster dependence was strong. The methods were applied to the bivariate failure times data from a diabetic retinopathy study.     

The market for construction wood in Mopti, Mali

This paper investigates the supply networks, the structure and operation of the markets and the increasing scarcity of good quality construction poles and hewn construction timber in Mopti, Mali. Using a variety of rapid appraisal methods the research identified separate groups of agents performing retailing, transporting and wood cutting functions within the supply network. A survey of the retail sector of the open or organised wood market in Mopti found the market to involve lower than expected volumes of timber and higher than expected mark-up variability across retailers and products. It was found that some users of construction wood do not buy their wood in the open market. The paper discusses one alternative method of obtaining wood involving the formation of a rural–urban solidarity network in which wood is ‘traded’ for various forms of help and assistance. The paper concludes that the re-empowerment of local communities so that they can manage and benefit from natural resources under their jurisdiction is probably a necessary condition for sustainable improvements in the supply of construction wood to Mopti. However, additional measures may be needed to replenish the stock of trees and human and institutional capital in the wood supply areas.     

Charismatic leadership: Eliciting and channeling follower emotions

Research on charismatic leadership has been criticized for the ambiguity of its central construct. Attempts to define and measure charisma have frequently treated it as a complex construct consisting of multiple components. However, little work has been done to develop a theoretical model that offers a parsimonious rationale explaining why certain leadership attributes are considered “charismatic” while others are not, or how these attributes combine to produce charismatic effects. Addressing these issues, we present a model that situates emotion as the primary variable in the charismatic process. We use recent research on the moral emotions to frame a theory of followership-relevant emotions (FREs) that describes how leaders use emotions such as compassion, admiration, and anger to compel their followers to act. We then discuss the Elicit-Channel (EC) model of charismatic leadership, positing that the charismatic relationship is a five-step, cyclical process. In the EC model, leaders elicit highly motivating emotions from their followers and then channel those emotions to produce action that, if successful, results in outcomes such as positive affect and trust. These outcomes then enable the leader to continue the cycle, eliciting emotion once more. We conclude by offering a research agenda, addressing potential methodological concerns, and discussing future directions.     

Flood risk mapping and analysis using an integrated framework of machine learning models and analytic hierarchy process

In this study, a new approach of machine learning (ML) models integrated with the analytic hierarchy process (AHP) method was proposed to develop a holistic flood risk assessment map. Flood susceptibility maps were created using ML techniques. AHP was utilized to combine flood vulnerability and exposure criteria. We selected Quang Binh province of Vietnam as a case study and collected available data, including 696 flooding locations of historical flooding events in 2007, 2010, 2016, and 2020; and flood influencing factors of elevation, slope, curvature, flow direction, flow accumulation, distance from river, river density, land cover, geology, and rainfall. These data were used to construct training and testing datasets. The susceptibility models were validated and compared using statistical techniques. An integrated flood risk assessment framework was proposed to incorporate flood hazard (flood susceptibility), flood exposure (distance from river, land use, population density, and rainfall), and flood vulnerability (poverty rate, number of freshwater stations, road density, number of schools, and healthcare facilities). Model validation suggested that deep learning has the best performance of AUC = 0.984 compared with other ensemble models of MultiBoostAB Ensemble (0.958), Random SubSpace Ensemble (0.962), and credal decision tree (AUC = 0.918). The final flood risk map shows 5075 ha (0.63%) in extremely high risk, 47,955 ha (5.95%) in high-risk, 40,460 ha (5.02%) in medium risk, 431,908 ha (53.55%) in low risk areas, and 281,127 ha (34.86%) in very low risk. The present study highlights that the integration of ML models and AHP is a promising framework for mapping flood risks in flood-prone areas.     

Shelter Provision in the Context of Deforestation: Some Evidence From Mali

Deforestation in many parts of the developing world has to led to a deterioration in both the quantity and the quality of wood (timber) available for housebuilding, threatening the viability of traditional building techniques. This paper examines the effects of a deteriorating resource base upon traditional house building practices in Mopti (Mali), where the most common traditional house type requires large quantities of strong and durable timber for the construction of the roof. It is shown that the favoured “rônier” wood is no longer accessible to the poorer sections of the population, who have no alternative but to use lower quality wood and less durable species. This in turn means more frequent replacement and maintenance, thus putting greater pressure on the available natural resources, and on household budgets. Those who cannot afford to maintain their houses, live in a state of insecurity due to the fear of collapse from poor construction. The implications for policy are explored, both in Mali and in the wider context. Options include support for the introduction of new building techniques and for the planting of trees which provide good timber for building.     

Automated Measurement of Facial Expression in Infant–Mother Interaction: A Pilot Study

Automated facial measurement using computer vision has the potential to objectively document continuous changes in behavior. To examine emotional expression and communication, we used automated measurements to quantify smile strength, eye constriction, and mouth opening in two 6‐month‐old infant‐mother dyads who each engaged in a face‐to‐face interaction. Automated measurements showed high associations with anatomically based manual coding (concurrent validity); measurements of smiling showed high associations with mean ratings of positive emotion made by naive observers (construct validity). For both infants and mothers, smile strength and eye constriction (the Duchenne marker) were correlated over time, creating a continuous index of smile intensity. Infant and mother smile activity exhibited changing (nonstationary) local patterns of association, suggesting the dyadic repair and dissolution of states of affective synchrony. The study provides insights into the potential and limitations of automated measurement of facial action.     

Corporate ownership,efficiency and performance under state capitalism: Evidence from China

This paper studied the relationship between business performance and the ownership structure of firms focusing on Chinese state owned enterprises (SOEs) using a firm level panel data set of China from 1999 to 2011. By classifying all firms into different types based on their ultimate controlling shareholders, we found that SOEs in general underperform in the marketplace than private enterprises. However, among the SOEs in our sample, the SOEs controlled by central government outperformed all types of firms because they offered the highest asset turnover ratio and lowest business administration ratio by receiving favourable government treatment. We conclude that firm ownership type and work efficiency are the main factors that influence the differences in firm performance. In particular, the performance of SOEs controlled by central government is greatly determined by the degree of government intervention, which is referred to as State Capitalism.     

Rank-based estimation for semiparametric accelerated failure time model under length-biased sampling

Length-biased sampling appears in many observational studies, including epidemiological studies, labor economics and cancer screening trials. To accommodate sampling bias, which can lead to substantial estimation bias if ignored, we propose a class of doubly-weighted rank-based estimating equations under the accelerated failure time model. The general weighting structures considered in our estimating equations allow great flexibility and include many existing methods as special cases. Different approaches for constructing estimating equations are investigated, and the estimators are shown to be consistent and asymptotically normal. Moreover, we propose efficient computational procedures to solve the estimating equations and to estimate the variances of the estimators. Simulation studies show that the proposed estimators outperform the existing estimators. Moreover, real data from a dementia study and a Spanish unemployment duration study are analyzed to illustrate the proposed method.     

Recurrence Relations And Identities For Moments Of Order Statistics,II; Specific Continuous Distributions

In an earlier paper, Malik et al. (1987) have reviewed several recurrence relations and identities available for the single and product moments of order statistics from an arbitrary continuous distribution. In this paper, we review several such relations and identities established for both single and product moments of order statistics from some specific continuous distributions. We also mention some important applications or. these results.     

Reciprocal interactions between group perceptions of leader charisma and group mood through mood contagion

Departing from the static perspective of leader charisma that prevails in the literature, we propose a dynamic perspective of charismatic leadership in which group perceptions of leader charisma influence and are influenced by group mood. Based on a longitudinal experimental study conducted for 3 weeks involving 116 intact, self-managing student groups, we found that T1 group perceptions of leader charisma mediate the effect of leader trait expressivity on T2 positive and negative group moods. T2 positive and negative group moods influence T3 distal charisma perceptions by affecting T2 proximal perceptions of leader effectiveness. The current findings offer critical insights into (a) the reciprocal relationship between group perceptions of leader charisma and group mood, (b) the dynamic and transient nature of group perceptions of leader charisma, (c) the importance of understanding negative mood in charismatic leadership, and (d) the mechanism through which charismatic leadership perceptions can be formed and sustained over time.