A Two-Latent-Class Model for Smoking Cessation Data with Informative Dropouts

Non ignorable missing data is a common problem in longitudinal studies. Latent class models are attractive for simplifying the modeling of missing data when the data are subject to either a monotone or intermittent missing data pattern. In our study, we propose a new two-latent-class model for categorical data with informative dropouts, dividing the observed data into two latent classes; one class in which the outcomes are deterministic and a second one in which the outcomes can be modeled using logistic regression. In the model, the latent classes connect the longitudinal responses and the missingness process under the assumption of conditional independence. Parameters are estimated by the method of maximum likelihood estimation based on the above assumptions and the tetrachoric correlation between responses within the same subject. We compare the proposed method with the shared parameter model and the weighted GEE model using the areas under the ROC curves in the simulations and the application to the smoking cessation data set. The simulation results indicate that the proposed two-latent-class model performs well under different missing procedures. The application results show that our proposed method is better than the shared parameter model and the weighted GEE model.     

A Dynamic Latent Model for Poverty Measurement

The main purpose of this paper is the longitudinal analysis of the poverty phenomenon. By interpreting poverty as a latent variable, we are able to resort to the statistical methodology developed for latent structure analysis. In particular, we propose to use the mixture latent Markov model which allows us to achieve two goals: (i) a time-invariant classification of households into homogenous groups, representing different levels of poverty; (ii) the dynamic analysis of the poverty phenomenon which highlights the distinction between transitory and permanent poverty situations. Furthermore, we exploit the flexibility provided by the model in order to achieve the measurement of poverty in a multidisciplinary framework, using several socio-economic indicators as covariates and identifying the main relevant factors which influence permanent and transitory poverty. The analysis of the longitudinal data of the Survey on Households Income and Wealth of the Bank of Italy provides the identification of two groups of households which are characterized by different dynamic features. Moreover, the inclusion of socio-economic covariates such as level of education, employment status, geographical area and residence size of the household head shows a direct association with permanent poverty.     

Depression and Missed Work among Informal Caregivers of Older Individuals with Dementia

Although providing informal care can negatively affect caregiver emotional health and lead to depression, the association between caregiver depression and missed work is unknown. We use data from the National Longitudinal Caregiver Survey to examine the relationship between caregiver depression and missed work among informal caregivers for older veterans with Alzheimer’s disease or vascular dementia. Two-part models are used to estimate the expected hours of work missed among working caregivers. Caregiver depression is statistically significantly associated with the likelihood and amount of time missed at work, resulting in an average of an extra half-day of work missed per month. While the effect of caregiver depression on work missed is modest, it represents another possible benefit from interventions to support caregivers.     

The Welsh Patagonian Connection: A Neglected Chapter in Australian Immigration History

This article is an account of the history of Welsh migrants to Patagonia from 1865 to 1914, their motivations for emigrating, their experiences in Argentina, and the subsequent relocation of several hundred to the British dominions in the early twentieth century.
The focus in the first part of the article is on the nature of those who went from Patagonia to Australia between 1910 and 1915 and the migration of a group of Australians to Paraguay in the 1890s. The second half of the article examines the experiences of the Welsh Patagonians in Australia, their relationships with federal and state governments in the light of the intense rivalry to procure them as settlers, and their involvement in two New South Wales Royal Commissions concerning the operations of the Murrumbidgee Irrigation Area.
The article concludes with a discussion on the degree to which a Welsh cultural heritage and identity has been preserved by these settlers in an assimilationist post-Federation Australia. Not only is this a unique double migration experience, but it calls into question immigration encouragement policies and official advertising material during this period, a history which parallels other land settlement schemes of both the pre- and post-war eras in Australia.     

Uncovered set choice rules

I study necessary and sufficient conditions for a choice function to be rationalized in the following sense: there exists a total asymmetric relation T (a tournament) such that, for each feasible (finite) set, the choice set coincides with the uncovered set of T restricted to that feasible set. This notion of ‘maximization’ offers testable restrictions on observable choice behavior.     

Quantity quantiles linear regression

We show that the definition of the θth sample quantile as the solution to a minimization problem introduced by Koenker and Bassett (Econometrica 46(1):33–50, 1978) can be easily extended to obtain an analogous definition for the θth sample quantity quantile widely investigated and applied in the Italian literature. The key point is the use of the first-moment distribution of the variable instead of its distribution function. By means of this definition we introduce a linear regression model for quantity quantiles and analyze some properties of the residuals. In Sect. 4 we show a brief application of the methodology proposed. This research was partially supported by Fondo d’Ateneo per la Ricerca anno 2005—Università degli Studi di Milano-Bicocca. The paper is the result of the common work of the authors; in particular M. Zenga has written Sects. 1 and 5 while P. Radaelli has written the remaining sections.     

Leader–member exchange and empowerment: Direct and interactive effects on job satisfaction,turnover intentions,and performance

This study examined the moderating impact of empowerment on the relationships between leader–member exchange (LMX) quality and the self-rated outcomes of job satisfaction and turnover intentions, as well as the supervisor-rated outcomes of job performance and organizational citizenship behaviors. Two samples, with 244 and 158 employees respectively, were used to test our hypotheses. Our results provided evidence that in general, empowerment moderates the relationships between LMX and job outcomes. These findings are important as previous research has only tested these variables as independent predictors, but our results suggest the relationships these constructs have with important consequences are dependent on both variables. Practical implications and directions for future research are offered.     

Are clinician's ever biased in their judgments of the capacity of older adult's to make medical decisions?

Capacity assessment is a growing area of practice in geriatrics. In this pilot study we illustrate the potential relationship between clinician variables and capacity ratings. Twelve older adults with mild dementia or schizophrenia were rated by six clinicians from diverse disciplinary backgrounds. Capacity ratings were associated with clinician values regarding patient involvement in medical decisions, clinician-patient mismatches on such values, and emotional reactions to patients. Expanding our understanding of the impact of clinician variables on capacity ratings may enhance the reliability and validity of capacity assessments and help to promote autonomy when appropriate.     

Strategies Used by Gay and Bisexual Young Men to Cope with Heterosexism

Although the pervasiveness of heterosexism in the lives of gay and bisexual youth is well established, little is known about the strategies these youth use to cope with stigma and discrimination based on their sexual minority status. In this qualitative study, the authors present findings and implications for clinical practice based on interviews with 43 gay and bisexual young men. Respondents' coping strategies are discussed in relation to current theory and research on coping with stigma, as well as the emerging field of emotion regulation. The narratives from the current study suggest that the emotion regulation paradigm is well suited to understanding the functions of strategies for coping with heterosexism and similar types of stigma.