Application of a non-homogeneous Markov chain with seasonal transition probabilities to ozone data

In this work, we assume that the sequence recording whether or not an ozone exceedance of an environmental threshold has occurred in a given day is ruled by a non-homogeneous Markov chain of order one. In order to account for the possible presence of cycles in the empirical transition probabilities, a parametric form incorporating seasonal components is considered. Results show that even though some covariates (namely, relative humidity and temperature) are not included explicitly in the model, their influence is captured in the behavior of the transition probabilities. Parameters are estimated using the Bayesian point of view via Markov chain Monte Carlo algorithms. The model is applied to ozone data obtained from the monitoring network of Mexico City, Mexico. An analysis of how the methodology could be used as an aid in the decision-making is also given.     

Financial Well-Being Index in México

Social Indicators Research - This paper aims to construct a financial well-being index and analyze its determinants among adults in Mexico. It employs multiple correspondence analysis, multiple...     

A generalized Fleming and Harrington's class of tests for interval‐censored data

The class $G^{\rho,\lambda }$ of weighted log‐rank tests proposed by Fleming & Harrington [Fleming & Harrington (1991) Counting Processes and Survival Analysis, Wiley, New York] has been widely used in survival analysis and is nowadays, unquestionably, the established method to compare, nonparametrically, k different survival functions based on right‐censored survival data. This paper extends the $G^{\rho,\lambda }$ class to interval‐censored data. First we introduce a new general class of rank based tests, then we show the analogy to the above proposal of Fleming & Harrington. The asymptotic behaviour of the proposed tests is derived using an observed Fisher information approach and a permutation approach. Aiming to make this family of tests interpretable and useful for practitioners, we explain how to interpret different choices of weights and we apply it to data from a cohort of intravenous drug users at risk for HIV infection. The Canadian Journal of Statistics 40: 501–516; 2012 © 2012 Statistical Society of Canada     

Simultaneous marginal survival estimators when doubly censored data is present

A doubly censoring scheme occurs when the lifetimes T being measured, from a well-known time origin, are exactly observed within a window [L, R] of observational time and are otherwise censored either from above (right-censored observations) or below (left-censored observations). Sample data consists on the pairs (U, δ) where U = min{R, max{T, L}} and δ indicates whether T is exactly observed (δ = 0), right-censored (δ = 1) or left-censored (δ = −1). We are interested in the estimation of the marginal behaviour of the three random variables T, L and R based on the observed pairs (U, δ). We propose new nonparametric simultaneous marginal estimators [^(S)]_T, [^(S)]_L{\hat S_{T}, \hat S_{L}} and [^(S)]_R{\hat S_{R}} for the survival functions of T, L and R, respectively, by means of an inverse-probability-of-censoring approach. The proposed estimators [^(S)]_T, [^(S)]_L{\hat S_{T}, \hat S_{L}} and [^(S)]_R{\hat S_{R}} are not computationally intensive, generalize the empirical survival estimator and reduce to the Kaplan-Meier estimator in the absence of left-censored data. Furthermore, [^(S)]_T{\hat S_{T}} is equivalent to a self-consistent estimator, is uniformly strongly consistent and asymptotically normal. The method is illustrated with data from a cohort of drug users recruited in a detoxification program in Badalona (Spain). For these data we estimate the survival function for the elapsed time from starting IV-drugs to AIDS diagnosis, as well as the potential follow-up time. A simulation study is discussed to assess the performance of the three survival estimators for moderate sample sizes and different censoring levels.     

Freedom,Identity, and the Social History of Empire in Atlantic Cuba, 1795–1817

This essay examines a maritime case involving a Charleston-based French privateer in 1795 as well as members, subjects, and citizens of multiple societies from Western Africa, Cuba, Spain, and Great Britain in order to reveal the fluid legal foundations of trans-Atlantic regimes with respect to slavery and freedom. The French maritime seizure of a British slaving vessel in the Caribbean and the subsequent transfer of enslaved African peoples from British to French to Spanish authority in Cuba set the stage for nearly 40 years of litigation in both hemispheres. The case led to legal disputes in Philadelphia, Madrid, and Havana as members of this Atlantic society sought to confront the most prominent political and social issues of this era. While officials in Philadelphia sought to avoid entanglement in the imperial wars between France and Great Britain, officials in Madrid and Havana competed with each other in order to define the legal identities of a group of Carabalí-Oru peoples onboard the British vessel. For their part, this group of Carabalí-Oru peoples exploited the ambiguities created by a system of Atlantic jurisprudence while relying on their memory of the Middle Passage in order to challenge their unjust enslavement in Cuba.     

HOW DOES PRODUCT MARKET COMPETITION SHAPE INCENTIVE CONTRACTS?

This paper studies the effect of product market competition on the explicit compensation packages that firms offer to their CEOs, executives and workers. We use a large sample of both traded and nontraded UK firms and exploit a quasi‐natural experiment associated to an increase in competition. The sudden appreciation of the pound in 1996 implied different changes in competition for sectors with different degrees of openness. Our difference in differences estimates show that a higher level of product market competition increases the performance pay sensitivity of compensation schemes, in particular for executives. (JEL: J33, L20, G34)     

Interval censoring: Model characterizations for the validity of the simplified likelihood

In survival data analysis, the interval censoring problem has generally been treated via likelihood methods. Because this likelihood is complex, it is often assumed that the censoring mechanisms do not affect the mortality process. The authors specify conditions that ensure the validity of such a simplified likelihood. They prove the equivalence between different characterizations of noninformative censoring and define a constant‐sum condition analogous to the one derived in the context of right censoring. They also prove that when the noninformative or constant‐sum condition holds, the simplified likelihood can be used to obtain the nonparametric maximum likelihood estimator of the death time distribution function.     

Social security reform and the support for public education

Old age pensions and public education account for a large share of public budgets. We link both programs through a tax-transfer system that is also sensitive to labor market distortions. We analyze the impact that alternative pension reforms have, through the political process, on publicly financed education. We explain how changes in the pension system design affect the link between the two programs and also labor market incentives. These effects, if they exist, act in opposite directions. Overall, we find that most proposals that entail a partial privatization of pensions reduce the willingness of the society to fund public education.     

Disparities in the Quality of Pediatric Dental Care: New Research and Needed Changes

In the United States, there are significant disparities in the oral health of children from families with high and low socioeconomic status and between majority and minority children. Extant research on these health differences has focused predominately on caregiver knowledge, beliefs, and practices as well as structural barriers such as Medicaid coverage, dentist availability, and transportation issues. Little attention has been paid to the quality of care families experience when taking their child to the dentist or the ways in which dental schools train their students to work with young children. This policy report describes some of the experiences of low-income and ethnically diverse young children and their parents in dental clinics and highlights some of the weaknesses of dental training. We contend that increasing the standards for dental training and practice are necessary for improving young children's oral health and reducing these disparities.     

A temporary contraction in the number of Peruvian births circa 1990: documenting a previously undetected event

In the 1980s, Peru experienced a deep economic crisis and an extremely violent political climate with armed confrontation. As suggested by the literature, it would be reasonable to expect a temporary contraction in the number of births during this period; however, the official population estimates do not show that behaviour. Relying on three different sources (generated independently by diverse organisations in different moments and using varied methods), this article finds consistent evidence suggesting there was a contraction in fertility that has not been previously accounted for. The article also estimates the size of said contraction.