Hypothesis test for paired samples in the presence of missing data

Missing data are present in almost all statistical analysis. In simple paired design tests, when some subject has one of the involved variables missing in the so-called partially overlapping samples scheme, it is usually discarded for the analysis. The lack of consistency between the information reported in the univariate and multivariate analysis is, perhaps, the main consequence. Although the randomness on the missing mechanism (missingness completely at random) is an usual and needed assumption for this particular situation, missing data presence could lead to serious inconsistencies on the reported conclusions. In this paper, the authors develop a simple and direct procedure which allows using the whole available information in order to perform paired tests. In particular, the proposed methodology is applied to check the equality among the means from two paired samples. In addition, the use of two different resampling techniques is also explored. Finally, real-world data are analysed.     

Clinical Gender Differences Among Adult Pathological Gamblers Seeking Treatment

This study aimed to examine the gender-related differences in demographics, gambling measures, psychological functioning, and motivation for therapy in an outpatient sample of pathological gamblers seeking treatment. Participants in this multisite study included 103 adult outpatients (51 women and 52 men) meeting current DSM-IV-TR criteria for PG. Logistic regression was used to examine if gender was related together to categorical and continuous independent variables. Female gamblers were older than men and more likely to be divorced or widowed and to have a lower annual income. Women became more dependent on bingo and men on slot machines. Gambling motivation and the course of illness for both sexes were also different. Female gamblers were more anxious and with a poorer self-esteem than male gamblers and more affected by depressive symptoms; in turn, men were more impulsive and higher sensation seekers than women and more affected by drug/alcohol abuse. The 68.6% of female gamblers reported being victims of intimate partner violence. There were no gender differences about the motivation for treatment. Future research should examine gambling behaviors and psychological functioning and suggest treatment approaches to address specific goals according to these gender-related differences.     

Powerful nonparametric statistics to compare k independent ROC curves

The authors deal with the problem of comparing receiver operating characteristic (ROC) curves from independent samples. From a nonparametric approach, they propose and study three different statistics. Their asymptotic distributions are obtained and a resample plan is considered. In order to study the statistical power of the introduced statistics, a simulation study is carried out. The (observed) results suggest that, for the considered models, the new statistics are more powerful than the usually employed ones (the Venkatraman test and the usual area under the ROC curve criterion) in non-uniform dominance situations and quite good otherwise.     

The Benefits and Costs of Using Metadata to Improve Enterprise Document Search

The literature shows that there are many problems with enterprise document search. Studies reveal that typical knowledge workers spend between 10% and 20% of their time searching for documents they never find. While many argue that metadata can improve enterprise document search, in reality few organizations use metadata. This represents a missed opportunity. This article describes the results of two experiments that use simulation to evaluate the actual impact of metadata on the costs and benefits of enterprise search. The first study provides quantitative evidence of the increase in recall and precision that stems from the use of metadata‐enhanced document searches. The second study demonstrates that simple metadata structures can be nearly as effective as complex ones, implying that the cost of creating and maintaining metadata is likely to be lower than generally thought. This is the first study to provide explicit quantitative evidence of the gains that can be achieved from the use of metadata, and one of only a handful of studies that examines the cost of creating and maintaining metadata.     

A general bootstrap algorithm for hypothesis testing

The bootstrap is a intensive computer-based method originally mainly devoted to estimate the standard deviations, confidence intervals and bias of the studied statistic. This technique is useful in a wide variety of statistical procedures, however, its use for hypothesis testing, when the data structure is complex, is not straightforward and each case must be particularly treated. A general bootstrap method for hypothesis testing is studied. The considered method preserves the data structure of each group independently and the null hypothesis is only used in order to compute the bootstrap statistic values (not at the resampling, as usual). The asymptotic distribution is developed and several case studies are discussed.     

Assessing the Role of Tourism in Poverty Alleviation: A Research Agenda

Understanding the tourism‐poverty link is critical if tourism is to be used as a mechanism for reducing poverty. Yet, the available empirical analysis is insufficient for this. This article proposes a research agenda for closing this gap in the literature. It argues that, while analysing the link poses peculiar challenges, models exist to do so. Second, it contends that the key question is not whether the link exists but under what conditions it is strongest. Finally, it maintains that the best way to analyse the link is to incorporate accurate diagnosis and evaluations into tourism projects, using the approaches and concepts of the literature on impact evaluation.     

Constraints and opportunities for civic and political participation: perceptions of young people from immigrant and non-immigrant background in Portugal

Youth civic and political participation (CPP) has been a central concern of research and public policy. This situation has been motivated by growing signs of the disaffection of younger generations, at least regarding conventional forms of participation. Recent theoretical debates stress how forms of CPP are evolving; nevertheless it is obviously important to integrate young people's views in the discussion, particularly taking into account groups at risk of exclusion, such as immigrants. This paper intends to contribute to this discussion by considering the meanings that young people attribute to their civic and political experiences, using data collected with focus groups (N = 94) that address the factors that facilitate and/or inhibit the participation of young people from immigrant (Brazilian and Angolan) and non-immigrant (Portuguese) backgrounds. Data will be analysed according to three main dimensions: (1) participants' sources of knowledge, information and influence; (2) participants' views on civic and political engagement: relevance, resources, personal experiences, trustworthiness and efficacy; and (3) participants' perceptions of excluded groups and proposals to promote inclusion. Results show that the experiences and levels of participation of young people of Brazilian and Angolan origin are influenced by their immigrant background. In addition, they indicate a strong tendency of young people to emphasise constraints over opportunities. They feel like incomplete or in-the-making citizens, and state their claim for rights and opportunities to be heard and to be civic and politically engaged.