The generalized odd log-logistic family of distributions: properties,regression models and applications

We propose a new class of continuous distributions with two extra shape parameters named the generalized odd log-logistic family of distributions. The proposed family contains as special cases the proportional reversed hazard rate and odd log-logistic classes. Its density function can be expressed as a linear combination of exponentiated densities based on the same baseline distribution. Some of its mathematical properties including ordinary moments, quantile and generating functions, two entropy measures and order statistics are obtained. We derive a power series for the quantile function. We discuss the method of maximum likelihood to estimate the model parameters. We study the behaviour of the estimators by means of Monte Carlo simulations. We introduce the log-odd log-logistic Weibull regression model with censored data based on the odd log-logistic-Weibull distribution. The importance of the new family is illustrated using three real data sets. These applications indicate that this family can provide better fits than other well-known classes of distributions. The beauty and importance of the proposed family lies in its ability to model different types of real data.     

Use of functional capacity evaluations in workplaces and the compensation system: a report on workers' and report users' perceptions

Until recently, little was documented about how functional capacity evaluations (FCEs) are used by employers and workers' compensation organizations. Such information was one focus of a comprehensive research study on FCEs carried out in southern Ontario, Canada, which involved representatives from the full range of groups involved in FCEs: referral sources, assessors, return-to-work specialists, third party payers and injured workers [1]. This paper shares findings from a cohort of injured workers undergoing FCEs, and explored how their FCE results were perceived and utilized by those receiving the reports. Based on study findings, we provide recommendations as to how FCEs should be requested, undertaken, reported and particularly applied to reduce work disability among injured workers.     

Generalized linear mixed models for correlated binary data with t-link

A critical issue in modeling binary response data is the choice of the links. We introduce a new link based on the Student’s t-distribution (t-link) for correlated binary data. The t-link relates to the common probit-normal link adding one additional parameter which controls the heaviness of the tails of the link. We propose an interesting EM algorithm for computing the maximum likelihood for generalized linear mixed t-link models for correlated binary data. In contrast with recent developments (Tan et al. in J. Stat. Comput. Simul. 77:929–943, 2007; Meza et al. in Comput. Stat. Data Anal. 53:1350–1360, 2009), this algorithm uses closed-form expressions at the E-step, as opposed to Monte Carlo simulation. Our proposed algorithm relies on available formulas for the mean and variance of a truncated multivariate t-distribution. To illustrate the new method, a real data set on respiratory infection in children and a simulation study are presented.     

Metabolic and hormonal responses to different resistance training systems in elderly men

Objective: To compare acute and sub-acute responses in hormonal profile and metabolic parameters in elderly people who participated in two methods of strength training (ST) with equalized loads.

Methods and materials: A total of 12 elder individuals (65?±?3 years) were randomly assigned to two training methods: constant intensity (CI, 3 sets of 10 repetitions with 75% of 1RM) and variable intensity (VI, 1st set: 12 repetitions at 67% of 1RM?>?2nd set: 10 repetitions at 75% of 1RM and 3rd set: 8 repetitions at 80% of 1RM). Both methods included the following exercises: leg press, knee extension, and squat with 1?min rest intervals between sets. Free speed of execution and maximum range of movement were encouraged throughout each set for both protocols. Blood samples were analyzed included glucose, testosterone (T), cortisol (C), T/C rate, growth hormone (GH), and lactate at 2 and 24?h post intervention.

Results: There were no observed differences in glucose, testosterone, GH, and lactate concentrations both at 2 and 24?h after the execution of the two training methods. However, significant increases in the levels of T/C rate and decrease on cortisol were observed immediately post exercise for both protocols.

Conclusions: Although no significant differences were observed between the two interventions in relation to the hormonal and metabolic parameters analyzed, both training methods promoted a favorable response, with a slight superiority noted for the CI method relative to the hormonal profile.     

Multi‐Family Therapy with a Reflecting Team: A Preliminary Study on Efficacy among Opiate Addicts in Methadone Maintenance Treatment

In this study, we evaluate the efficacy of multi‐family therapy at reducing the addiction severity and at improving the psychological and family dynamics of opiate addicts receiving methadone treatment at a public treatment center. The study compares multi‐family therapy with a reflecting team (MFT‐RT) and a standard treatment following a methadone maintenance treatment program. The results show that multi‐family therapy with a reflecting team effectively reduces the addiction severity in several of the areas evaluated and noted that this effect is superior to standard treatment. The psychotherapy patients showed improvement in the areas of employment and social support; their drug use diminished and their psychiatric condition improved. At the same time, they needed a lower daily dose of methadone. In addition, the group undergoing standard treatment showed a noteworthy deterioration in their medical condition. Both groups showed a significant increase in their alcohol use. When applied to family treatments, the systemic‐constructivist approach by the reflecting team offers combined techniques that can help improve care for the families of patients with addiction problems.     

Nonlinear mixed-effects models with scale mixture of skew-normal distributions

Aiming to avoid the sensitivity in the parameters estimation due to atypical observations or skewness, we develop asymmetric nonlinear regression models with mixed-effects, which provide alternatives to the use of normal distribution and other symmetric distributions. Nonlinear models with mixed-effects are explored in several areas of knowledge, especially when data are correlated, such as longitudinal data, repeated measures and multilevel data, in particular, for their flexibility in dealing with measures of areas such as economics and pharmacokinetics. The random components of the present model are assumed to follow distributions that belong to scale mixtures of skew-normal (SMSN) distribution family, that encompasses distributions with light and heavy tails, such as skew-normal, skew-Student-t, skew-contaminated normal and skew-slash, as well as symmetrical versions of these distributions. For the parameters estimation we obtain a numerical solution via the EM algorithm and its extensions, and the Newton-Raphson algorithm. An application with pharmacokinetic data shows the superiority of the proposed models, for which the skew-contaminated normal distribution has shown to be the most adequate distribution. A brief simulation study points to good properties of the parameter vector estimators obtained by the maximum likelihood method.     

Evaluating the impact of lean practices on environmental performance: evidences from five manufacturing companies

Abstract

Previous evidence suggests that lean practices help organizations to enhance environmental performance. However, the impact of lean practices on the environment is still unclear. This study, therefore, aims to analyse the relationship between lean and environmental performance in two main stages: first, a review of the relevant literature was developed, followed by a multiple case study analysis conducted in five manufacturing companies. Onsite data were collected from the firms during a 5 years’ time span of research and developing semi-structured interviews. Findings indicate that the environmental performance of the companies analysed is generally enhanced in the long-term after the implementation of lean. Moreover, the results suggest that the environmental performance of the firms investigated is mainly improved by using JIT and TQM practices in a lean transformation context. The research findings provide further results remarking the possible negative impact of Kanban deliveries, 5S and TPM on various environmental performance indicators.     

Reference database of hematological parameters for growing and aging rats

The normal hematological values in various phases of the rat life provide a valuable guide to researchers and could be useful for experimental works. However, database information available on the literature are incomplete. Aim: This study aimed to present normal hematological parameters of young and aged rats.

Methods: Male and female rats were distributed into seven experimental groups with 1, 2, 3, 6, 12, 18, and 24 months of age. Blood samples taken from the tails were analyzed. Normal hematological values were determined for each age group.

Results: Rats showed a progressive weight gain with advancing age, predominantly after 3 months of life. With advancing age, differences were found on hematological parameters: some of them showed a progressive rise with age and others did not. Hemoglobin levels and hematocrit did not change while the number of circulating red blood cells suffered slight increase.

Conclusion: The present study determined the normal values for absolute and relative hematological parameters in Wistar rats from 2 to 24 months for male and female rats. The results can be used in studies of effects of aging, feeding, and medications on growing and aging rats.     

Have cash transfers succeeded in reaching the poor in Latin America and the Caribbean?

We present original estimates of the quality of targeting of conditional cash transfer (CCT) and non‐contributory pension (NCP) programmes in Latin America and the Caribbean. Our contribution is novel because we use both national and international poverty lines; provide differentiated estimates for urban and rural areas; and compare the CCT and NCP programmes. We show that leakage to the non‐poor coexists with pervasive under‐coverage of all poor, including the extreme poor. On average, the CCTs cover only 50.5% of the extreme poor in households with children under 18 years of age. Similarly, the NCPs cover only 50.9% of the extreme poor in households with elderly members who do not receive a contributory pension. At the same time, 40.4% of CCT beneficiaries and 50.1% of NCP beneficiaries are not poor, highlighting the potential need for re‐targeting and re‐certification. In most countries, re‐targeting could produce a substantial double benefit in terms of poverty reduction and fiscal savings.