Exact Goodness‐of‐Fit Testing for the Ising Model

The Ising model is one of the simplest and most famous models of interacting systems. It was originally proposed to model ferromagnetic interactions in statistical physics and is now widely used to model spatial processes in many areas such as ecology, sociology, and genetics, usually without testing its goodness of fit. Here, we propose various test statistics and an exact goodness‐of‐fit test for the finite‐lattice Ising model. The theory of Markov bases has been developed in algebraic statistics for exact goodness‐of‐fit testing using a Monte Carlo approach. However, finding a Markov basis is often computationally intractable. Thus, we develop a Monte Carlo method for exact goodness‐of‐fit testing for the Ising model that avoids computing a Markov basis and also leads to a better connectivity of the Markov chain and hence to a faster convergence. We show how this method can be applied to analyze the spatial organization of receptors on the cell membrane.     

A procedure for estimating the number of outliers

A new type of procedure for estimating the number of outliers in a sample is presented and compared with existing procedures. The probabilities of exact, under-, and overestimation with the different procedures are examined for two different contamination schemes.     

A Multidimensional Approach to Measuring Quality of Employment (QoE) Deprivation in Six Central American Countries

This paper proposes a methodology for measuring Quality of Employment (QoE) deprivation from a multidimensional perspective in six Central American countries (Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama) using a dataset specifically designed to measure employment conditions. Building on previous work on multidimensional poverty and employment indicators, the paper uses the Alkire/Foster (AF) method to construct a synthetic indicator of the QoE at an individual level. It selects four dimensions that must be considered as essential to QoE deprivation: income, job stability, job security and employment conditions. These dimensions then subdivide into several indicators, a threshold for each indicator and dimension is established before defining an overall cut-off line that allows for the calculation of composite levels of deprivation. The results generated by this indicator show that Central American countries can be divided into three distinct and robust performance groups in terms of their QoE deprivation. Overall, approximately 60% of the deprivation levels are attributable to non-income variables, such as occupational status and job tenure. The methodology used can allow policymakers to identify and focus on the most vulnerable workers in a labour market and highlights the fact that having a formal written contract is no guarantee of good job quality, particularly in the case of women.

     

Overeducation as Status Inconsistency: Effects on Job Satisfaction,Subjective Well-Being and the Image of Social Stratification

Social Indicators Research - In this article, we aim to study the effects of the experience of overeducation, understood as a specific form of status inconsistency, in three areas: job...     

The duality of poverty: a replication of Mani et al. (2013) in Colombia

Theory and Decision - Scarcity acts as a mental burden that disrupts how people process information and make decisions (Mullainathan and Shafir in Scarcity: Why having too little means so much....     

Hurricane driven changes in vegetation structure and ecosystem services in tropical urban yards: a study case in San Juan,Puerto Rico

Urban forests are valuable spaces for species conservation, protection of local biodiversity and provision of ecosystem services. However, they are also vulnerable to the impact of extreme climate events like hurricanes. Understanding how urban forests are responding to hurricane disturbances is crucial to improve their design, management, and resilience. Here we analyzed pre-and post-hurricane vegetation surveys in 52 residential yards in San Juan to assess urban forest responses after Hurricanes Irma and María impacted Puerto Rico in 2017. We used these surveys to compare vegetation structure and composition (including species-specific mortality and damage rates) and to quantify changes in the ecosystem services provided by these yards. We found that hurricane disturbances significantly altered the structure but not the composition of yard vegetation. We detected a 27% reduction and 31% mortality of standing stems, and a significant reduction in plants health. Yard species composition was dominated by non-native species and this trend did not change with hurricane disturbance. Changes in vegetation structure translated into substantial reductions in ecosystem services. Food provision, an important service provided by a large proportion of yards before the hurricane, reported the highest reduction (41.9%) while carbon storage was the service that changed the least (9%). Our combined results emphasize the key role played by residential yards providing ecosystem services in tropical cities and call for further efforts to manage private and public urban forests in ways that may ensure their resilience to mitigate extreme climate events, provide multiple ecosystem services, and promote long-term urban sustainability.

     

Firth adjusted score function for monotone likelihood in the mixture cure fraction model

Lifetime Data Analysis - Models for situations where some individuals are long-term survivors, immune or non-susceptible to the event of interest, are extensively studied in biomedical research....     

A review of the CTP distribution: a comparison with other over- and underdispersed count data models

The complex triparametric Pearson (CTP) distribution is a flexible model belonging to the Gaussian hypergeometric family that can account for over- and underdispersion. However, despite its good properties, not much attention has been paid to it. So, we revive the CTP comparing it with some well-known distributions that cope with overdispersion (negative binomial, generalized Poisson and univariate generalized Waring) as well as underdispersion (Conway–Maxwell–Poisson (CMP) and hyper-Poisson (HP)). We make a simulation study that reveals the performance of the CTP and shows that it has its own space among count data models. In this sense, we also explore some overdispersed datasets which seem to be more appropriately modelled by the CTP than by other usual models. Moreover, we include two underdispersed examples to illustrate that the CTP can provide similar fits to the CMP or HP (sometimes even more accurate) without the computational problems of these models.     

Coherent Hypothesis Testing

Multiple hypothesis testing, an important quantitative tool to report the results of scientific inquiries, frequently leads to contradictory conclusions. For instance, in an analysis of variance (ANOVA) setting, the same dataset can lead one to reject the equality of two means, say μ₁ = μ₂, but at the same time to not reject the hypothesis that μ₁ = μ₂ = 0. These two conclusions violate the coherence principle introduced by Gabriel in 1969 Gabriel, K. R. (1969), “Simultaneous Test Procedures - Some Theory of Multiple Comparisons,” The Annals of Mathematical Statistics, 40, 224–250. Available at http://www.jstor.org/stable/2239213[Crossref] , [Google Scholar], and lead to results that are difficult to communicate, and, many times, embarrassing for practitioners of statistical methods. Although this situation is common in the daily life of statisticians, it is usually not discussed in courses of statistics. In this work, we enrich the teaching and discussion of this important topic by investigating through a few examples whether several standard test procedures are coherent or not. We also discuss the relationship between coherent tests and measures of support. Finally, we show how a Bayesian decision-theoretical framework can be used to build coherent tests. These approaches to coherence enlighten when such property is appealing in multiple testing and provide means of obtaining it.