bluuebunny/crossref_metadata_2025 huggingface dataset:
The Quest-(ion) for Diversity
Authors: Ali Amir
Published: November 2018

This article attempts to look at the quest for diversity by posing a question about how effective the concept has been in securing meaningful diversity in the public sphere of liberal polities. It distinguishes between diversity and difference to suggest that difference poses a greater challenge to liberal polities as compared to diversity. It then goes onto look at diversity in relation to democracy, especially in the context of a worsening climate of democracy across the world. The article suggests that the prospects for diversity are unlikely to be bright either in the contemporary conjuncture or the immediate future. The article ends by suggesting that diversity is caught between the forces of globalization and the insular nationalism that has welled up from the hinterlands of nation-states.
Russo/Nigerian Relations in the Context of Counterinsurgency Operation in Nigeria
Authors: Omotuyi Sunday
Published: November 2018

The effectiveness of Nigeria’s counterinsurgency operation has once again underscored the strategic importance of Russo-Nigerian relations. Having played a pivotal role in safeguarding the territorial unity of the country during its grueling civil war 1967–1970, Moscow’s importance in Nigeria’s national security in the post-Cold War period cannot be overemphasized. This article explores the dynamics of Russo-Nigerian relations in the context of current insurgency in the country. Drawing on extant literature and interview data from military chiefs, personnel of Nigeria’s Ministry of External Affairs, the study makes three arguments on why Russia agreed to Abuja’s request for arms for counterinsurgency operation in the face of Western disappointments. First, the convergence of interests between the two powers on the fight against terrorism. Second, Russia’s geopolitical calculation especially its quest for a new world multipolar order, and third, Russia’s economic doldrums occasioned by dwindling oil prices and Western economic sanctions in the wake of Crimean debacle. These overlapping factors are central to Russia’s strategic engagement with Nigeria. While the article notes that Moscow has cast itself as a Nigerian most dependable partner in security sector over the years, it concludes by urging Nigeria to strengthen relations with the country in all areas.
In whom do we trust? The level and radius of social trust among sport club members
Authors: Burrmann Ulrike , Braun Sebastian , Mutz Michael
Published: November 2018

This paper refers to the widespread notion that voluntary (sport) organizations produce social capital, popularized through the works of Robert D. Putnam, and compares social trust levels of sport club members with members in other voluntary associations and non-members. We differentiate between in-group trust and out-group trust, highlighting that not only the level of trust but also the “trust radius” counts for social cohesion in modern societies. Refining Putnam’s claims, we argue that social trust among members varies with the quality and intensity of participation captured (for instance, through volunteering), diverse social contacts and the level of membership trust experienced in an association. Based on a nation-wide survey, carried out in Germany during 2017/2018, it is demonstrated that members of civic associations indicate higher levels of trust towards in-groups and out-groups compared to non-members and they regard present society as more solidary and trusting. A fine-grained analysis among members of associations further shows that increased trust is typical for volunteers and individuals in socially diverse associations which, at the same time, are characterized by high levels of membership trust. We conclude that sports clubs need to provide beneficial context conditions for producing high levels and a wider radius of trust.
Eimeria gilruthi–associated abomasitis in a group of ewes
Authors: Ammar Sawsan I. , Watson Allison M. , Craig Linden E. , Cope Emily R. , Schaefer John J. , Mulliniks J. Travis , Gerhold Richard W.
Published: November 2018

Nine of 23 (39%) research ewes with severe diarrhea and weight loss had histologic lesions consistent with Eimeria gilruthi infection in their abomasa. Gross anatomic lesions included hundreds of opaque 1-mm nodules in abomasal mucosa that corresponded microscopically to 200–300 µm diameter organisms surrounded by areas of necrosis. Analysis of fecal samples from 4 ewes demonstrated oocysts from typical ovine Eimeria species, none of which were E. gilruthi. Two separate PCR reactions were performed on abomasal tissue from 4 sheep to amplify the 18S ribosomal DNA (rDNA) and internal transcribed spacer (ITS) region of the rDNA, respectively. The resultant 18S rDNA nucleotide sequences shared 99% homology with multiple Eimeria species in GenBank. The ITS region shared 77% homology with E. ellipsoidalis in GenBank. Further studies are needed to understand the life cycle and pathogenicity of E. gilruthi. Our results underscore the inclusion of E. gilruthi in the differential diagnosis of diarrhea and weight loss in sheep.
The Effect of 20-Minute Mindful Breathing on the Perception of Suffering and Changes in Bispectral Index Score in Palliative Care Patients: A Randomized Controlled Study
Authors: Beng Tan Seng , Jie How Wen , Yan Loo Hui , Ni Cheah Xin , Capelle David Paul , Yee Anne , Guan Ng Chong , Hasan Mohd Shahnaz bin , Seang Lim Kheng , Chin Loh Ee , Loong Lam Chee
Published: November 2018

A randomized controlled study was conducted to evaluate the efficacy of 20-minute mindful breathing in suffering reduction. Forty palliative care patients with an overall suffering score of 4 or above as measured with the Suffering Pictogram were recruited and randomly assigned to 20-minute mindful breathing or 20-minute supportive listening. There was statistically significant reduction of suffering score in both the groups. For Bispectral Index Score value, there was statistically significant difference between intervention and control. A 20-minute mindful breathing could be useful in the alleviation of suffering in palliative care.
The Influence of Mutuality on Self-Care in Heart Failure Patients and Caregivers: A Dyadic Analysis
Authors: Vellone Ercole , Chung Misook L. , Alvaro Rosaria , Paturzo Marco , Dellafiore Federica
Published: November 2018

Mutuality in patient–caregiver dyad may improve heart failure (HF) patient self-care and caregiver contribution to self-care, but literature is scarce. We evaluated the influence of mutuality and its dimensions on patient–caregiver dyad self-care. A sample of 366 HF patient–caregiver dyads was enrolled. The Actor–Partner Interdependence Model was used to identify the influence of individual patient and caregiver mutuality on their own self-care (actor effect) and on partner self-care (partner effect). The total mutuality score had an actor effect on patient self-care maintenance (i.e., behaviors aimed at maintaining HF stability) and on patient and caregiver self-care confidence. Total score of patient mutuality also had a partner effect on caregiver self-care management (i.e., responses to symptoms of HF exacerbation). Specific mutuality dimensions had different actor and partner effects on patient and caregiver self-care. Interventions to improve mutuality in HF patient–caregiver dyads may influence patient self-care and caregiver contribution to self-care.
Measuring Change in Nurses’ Perceptions About Family Nursing Competency Following a 6-Day Educational Intervention
Authors: Broekema Susanne , Luttik Marie Louise A. , Steggerda Gabriëlle E. , Paans Wolter , Roodbol Petrie F.
Published: November 2018

This study describes nurses’ perspectives about their experience of being involved in a 6-day educational intervention which focused on the development of competency in family nursing practice with a particular emphasis on family nursing conversations. The foundational knowledge of the educational intervention was based on the Calgary Family Assessment Model (CFAM) and the Calgary Family Intervention Model (CFIM). A research design incorporating quantitative and qualitative measurement was used. Before and after the family nursing educational intervention, nurse participants ( n = 18) completed the Families’ Importance in Nursing Care–Nurses’ Attitudes (FINC-NA) instrument. The outcomes were analyzed using paired-samples t tests. FINC-NA scores increased by 6.94 points ( SD = 5.66, p < .001). To complement the quantitative findings, in-depth interviews were conducted with all of the participants. Participants reported increased awareness of the importance of families in nursing care. In addition to an increase in positive attitudes about families, participants perceived that their knowledge and skills regarding family nursing conversations were more comprehensive. A 6-day educational intervention with a focus on reflection appears useful in helping nurses to “think family” and encouraging perceptions of increased competence in family nursing conversations.
Managing Customer Resource Endowments and Deficiencies for Value Cocreation: Complex Relational Services
Authors: Ng Sylvia C. , Sweeney Jillian C. , Plewa Carolin
Published: November 2018

The resources that customers have and are able to contribute or utilize may influence, shape, and determine the support that they receive from service providers. Yet, there is limited knowledge on the types of resources customers bring into the service process, that is, customer resource endowments and deficiencies, and how these relate to the service offered by providers. This study thus investigates the interplay and mobilization of specific resources between the customer and the service provider. Drawing on data from two online surveys in the financial planning and health-care contexts, the results demonstrate the fit between customer competencies measured in terms of sense of ownership, personal commitment, time availability, perceived complexity of situation, service-related skills, education, risk tolerance, and economic resources and the various service provider styles for value cocreation. Specifically, the discriminant maps show that service provider styles can best be differentiated not on the basis of a particular type of resource (i.e., physical, cultural, or economic) but rather according to a constellation of customer resource endowments and deficiencies. The insights provide unique opportunities for organizations to tailor support to customers’ resources and thus enhance value cocreation efforts.
Type and concentration effects of particulate solid lubricants on the microstructure, friction, and wear of electrodeposited Ni composite coatings
Authors: Trabelsi Dorra , Zouari Manel , Kharrat Mohamed , Dammak Maher , Eyraud Marielle , Vacandio Florence
Published: November 2018

Nickel–MoS2 composite coatings were obtained by electrodeposition from a nickel electrolyte containing suspended MoS2 particles. The coating composition, morphology, crystalline structure, microhardness, and frictional behavior were studied as a function of MoS2 concentration. The results obtained in this study revealed that the codeposited lubricant particles strongly influenced the composite nickel coating properties. It was found that increasing codeposited MoS2 decreases the average grain size of nickel crystallites and leads to the formation of clusters which, in turn, lead to rough coatings with a high and variable thickness. The results of tribological response indicated that the reduction of friction coefficient and the improvement of wear resistance were performed until an optimal value of MoS2 concentration, which provided the best condition that promoted the tribo-layer stability and maintained the matrix integrity. A comparison of tribological and micromechanical properties between the coating containing the optimal fraction of MoS2 particles and the coating containing nearly the same fraction of graphite particles has been undertaken. Unlike the case of the addition of graphite particles, the microhardness of composite coating has been enhanced with the incorporation of MoS2 particles. However, the incorporation of graphite particles in the coating induced more effective lubrication and wear resistance.
Modeling of the drag torque of the disengaged grooved wet clutches with waviness
Authors: Wang Yanzhong , Ren Shaoying , Li Yuan
Published: November 2018

It is seen that the relative motion between the friction and separate plates causes drag torque of the disengaged wet clutch, which reduces the efficiency of the automatic transmission. A mathematical model of the drag torque was presented in this paper to study the effects of the grooves and waviness on the friction plate during the disengagement of the wet clutch. The modified Reynolds equation of the lubricant film was derived from the governing equations by considering the centrifugal effect. The finite difference method was applied to solve Reynolds equation, and the shape and size of groove and waviness on the friction plates were described by the thickness of lubricant film at each mesh point in the numerical solution. Equivalent outer radius was introduced to estimate the drag torque of the disengaged wet clutch based on Newton's internal friction theorem. The influencing factors including groove shapes, groove depth and width, waviness, lubricant viscosity, and supply flow were discussed to analyze their effects on the drag torque of the disengaged wet clutch. An experimental rig was set up to test the drag torque of the grooved wet clutch and results indicated that the theoretical drag torque had good agreement with the experimental data.
Lubrication performance of planar thrust bearing with consideration of roughness of the surfaces
Authors: Li Shanshan , An Qi
Published: November 2018

Based on the numerical simulation of the rough surfaces, Reynolds equation and Newton's Second Law of Motion-Force and Acceleration, the calculation model for planar thrust sliding bearing considering microcosmic topography is established in this paper. A method for calculating the acceleration of bearing is presented. By a specific example, the changes of the oil film pressure, acceleration and additional load of the thrust bearing during rotating are numerically calculated by the MATLAB program. The influences of rotation speed, surface roughness, and rotor mass on the lubrication performance of thrust sliding bearing were studied in detail.
Forecasting tourist arrivals at attractions: Search engine empowered methodologies
Authors: Volchek Katerina , Liu Anyu , Song Haiyan , Buhalis Dimitrios
Published: November 2018

Tourist decision to visit attractions is a complex process influenced by multiple factors of individual context. This study investigates how the accuracy of tourism demand forecasting can be improved at the micro level. The number of visits to five London museums is forecast and the predictive powers of Naïve I, seasonal Naïve, seasonal autoregressive moving average, seasonal autoregressive moving average with explanatory variables, SARMAX-mixed frequency data sampling and artificial neural network models are compared. The empirical findings extend understanding of different types of data and forecasting algorithms to the level of specific attractions. Introducing the Google Trends index on pure time-series models enhances the forecasts of the volume of arrivals to attractions. However, none of the applied models outperforms the others in all situations. Different models’ forecasting accuracy varies for short- and long-term demand predictions. The application of higher frequency search query data allows for the generation of weekly predictions, which are essential for attraction- and destination-level planning.
‘I Will Not Be Thrown Out of the Country Because I’m an Immigrant’: Eastern European Migrants’ Responses to Hate Crime in a Semi-Rural Context in the Wake of Brexit
Authors: Lumsden Karen , Goode Jackie , Black Alex
Published: November 2018

This article examines Eastern European migrants’ experiences of and responses to hate crime. Following the UK European Union Membership Referendum (‘Brexit’ vote), there was an increase in reported hate crimes against immigrants. The study focuses on the experiences of migrants in Lincolnshire, a region of England which has a significant migrant population, and which had one of the highest ‘leave’ votes. The focus on white migrants in this semi-rural setting offers an original perspective in the field of hate crime studies. We draw on semi-structured interviews and observations to identify temporal, spatial, and relational factors in responses to hate crime. We uncover the insecure occupation of a ‘third space’ constituted by material, discursive, and emotional practices. This positioning was destabilised post referendum; but there was also evidence of the operation of agency within processes of ‘othering’, suggesting a transition from victim identity to emergent political subject.
Liberation or purification? Prostitution, women’s movement and nation building in South Korea under US military occupation, 1945–1948
Authors: Park Jeong-Mi
Published: November 2018

This article investigates postcolonial South Korea’s prostitution policy as a focal point of sexual politics in the undertaking of nation building under US military occupation (1945–1948). It clarifies that the discourse on prostitution served as a forum for competing visions of a new nation: socialism versus nationalism, and women’s liberation versus national purification. It analyzes the paradoxical process by which the women’s campaign to abolish one colonial legacy of prostitution (‘Authorization-Regulation’) eventually resulted in retaining another legacy (‘Toleration-Regulation’) in a new guise. It conceptualizes the postcolonial prostitution policy that combined regulation and prohibition as a ‘Toleration-Regulation Regime,’ arguing that it was a compromise between the US military government and South Korean elites. Finally, this article demonstrates that building the nation was also a process of making female subalterns, prostitutes.
Nurturing the erotic self: Benefits of women consuming sexually explicit materials
Authors: Chesser Stephanie , Parry Diana , Penny Light Tracy
Published: November 2018

Using a feminist standpoint theoretical orientation, we explored the ways consumption of sexually explicit materials (SEM) could be beneficial to women’s overall well-being. For this study, 28 women were recruited from two female-oriented sexual health education establishments in Ontario, Canada and asked to participate in qualitative interviews. Our findings suggest that women derive personal and social benefits from their engagement with SEM. Overall, this research draws attention to the ways SEM consumption may strengthen women’s sexual subjectivity and provide outlets for women to learn about and experiment with their bodies and erotic selves.
Life course perspectives on (bi)sexuality: Methodological tools to deprivilege current identities
Authors: Jones Rebecca L
Published: November 2018

Scholars of sexuality have known for many years that sexual identity claims do not map neatly on to sexual histories. However, many studies continue to use currently claimed sexual identities as the basis for data collection and analysis, which can erase this complexity, particularly in relation to bisexuality. This article identifies four methodological techniques that help to operationalise theoretical sensitivity around the complex relationship between identities and histories. It does so by bringing together life course perspectives and two mixed methods datasets from older people with bisexual histories. Combining life course perspectives with these unusual datasets makes evident the particular way in which moment-in-time perspectives oversimplify sexuality and privilege monosexual identities. A life course approach thus helps to explain a long-standing puzzle in the study of sexuality: the relative under-claiming of bisexual identities compared to the prevalence of bisexual behaviours. Furthermore, it offers methodological tools that facilitate richer theorisations of sexuality more widely.
Liquid Love: Zygmunt Bauman’s thesis on sex revisited
Authors: Best Shaun
Published: November 2018

In Liquid Love, Zygmunt Bauman (2003) argued that within liquid modernity a consumer driven, adiaphoric, sexual free for all had emerged, rooted in an intense unregulated individualism. Sexuality was identified by Bauman as one of the areas of social life that had become privatized; that the state had withdrawn from regulation. Liquid Love is identified as one application too far for Bauman’s liquefaction thesis in that the book highlights the commonality that exists between solid and liquid modernity in terms of the regulation of personal life. In contrast to Bauman’s thesis, more sexual activities have become criminalized, people previously marginalized as sexually the Other are encouraged to incorporate their relationships within previously heterosexual arrangements such as marriage and more populations are regulated in terms of their most intimate of behaviours.
Hospital admissions and surgical treatment of children with lower-limb deficiency in Finland
Authors: Syvänen J. , Helenius I. , Koskimies-Virta E. , Ritvanen A. , Hurme S. , Nietosvaara Y.
Published: November 2018

Background and Aims:

There are no population-based studies about hospital admissions and need for surgical treatment of congenital lower-limb deficiencies. The aim is to assess the impact children with lower-limb deficiencies pose to national hospital level health-care system.

Materials and Methods:

A population-based study was conducted using the national Register of Congenital Malformations and Care Register for Health Care. All 185 live births with lower-limb deficiency (1993–2008) were included. Data on hospital care were collected until 31 December 2009 and compared to data on the whole pediatric population (0.9 million) live born in 1993−2008.

Results:

The whole pediatric population had annually on average 0.10 hospital admissions and the mean length of in-patient care of 0.3 days per child. The respective figures were 1.5 and 5.6 in terminal lower-limb amputations (n = 7), 1.1 and 3.9 in long-bone deficiencies (n = 53), 0.6 and 1.9 in foot deficiencies (n = 26) and 0.4 and 2.6 in toe deficiencies (n = 101). Orthopedic surgery was performed in 72% (5/7) of patients with terminal amputations, in 62% (33/53) of patients with long bone, in 58% (14/24) of patients with foot and in 25% (25/101) of patients in toe deficiencies. Half (54%) of all procedures were orthopedic operations.

Conclusion:

In congenital lower-limb deficiencies the need of hospital care and the number of orthopedic procedures is multiple-fold compared to whole pediatric population. The burden to the patient and to the families is markedly increased, especially in children with terminal amputations and long-bone deficiencies of lower limbs.
From learning to labour to custody for the precariat
Authors: Sernhede Ove
Published: November 2018

The globally reported riots in the poor high-rise suburbs of Sweden’s metropolitan districts in 2013 were stark manifestations of the increased social and economic inequality of the past 30 years. Large groups of young adults acted out their unarticulated claims for social justice. In the light of the riots, it is relevant to ask whether any trace of resistance or protest can be found in the compulsory school where the young people from these neighbourhoods spend their days. The ethnography sampled for the article comes from two public schools in two poor, multi-ethnic, high-rise neighbourhoods on the outskirts of Gothenburg. The article argues that the theoretical and methodological concepts and perspectives developed by Willis still is of crucial importance to any investigation aimed at understanding the presence or absence of resistance in contemporary Swedish schools.
Multimodal methodological approach for participatory design of Full-Body Interaction Learning Environments
Authors: Malinverni Laura , Schaper Marie-Monique , Pares Narcis
Published: November 2018

Over the past years an increasing number of digital learning environments based on Full-Body Interaction have been developed. Research in this field is often based on Designer-Driven approaches and is only recently employing Participatory Design techniques. However, these participatory approaches have reported relevant challenges related to including users in the design of spatial and bodily qualities of interaction. These shortcomings require extending research methods to effectively focus on embodied resources in the essential design and evaluation processes. To address this issue, we propose a methodological approach that combines multimodal analysis with Participatory Design techniques to include embodied resources in the participatory design processes for Full-Body Interaction. The proposed approach is applied to the iterative design of two Full-Body Interaction Learning Environments. Through the analysis of the outcomes of these case studies, we discuss the affordances multimodal analysis can offer to inform and guide the design process for embodied interaction.
‘Now the German comes’: The ethnic effect of gentrification in Berlin
Authors: Polat Defne Kadıoğlu
Published: November 2018

Compared to the United States, the relationship between ethnicity and gentrification is still understudied in the Western European context. However, while Western Europe does not have the same racial history as the United States, ethnic and racial divisions are still expressed through urban inequality. This paper, a study of small-business owners in an ethnically stigmatized Berlin neighborhood, shows how the gentrification process leads to the revelation and reification of ethnic boundaries between Turkish immigrants and their descendants and the so-called German majority society. It firstly finds that gentrification by Turkish-origin business owners is frequently understood as an ethnic remake that leads to the displacement of Turkish immigrants and their families in favor of non-immigrant Germans. The gentrification process is accordingly perceived, not only as a form of material dispossession, but also as a form of cultural dispossession in which the multicultural character of the quarter is erased. Second, the paper postulates that, in cases in which Turkish immigrant entrepreneurs adapt their businesses to the demands of new middle-class consumers, they tend to exclude the lower-income population in the quarter whom they mainly define as Turkish or Arabic. All in all, the debate presented in this paper shows how, in the German context, gentrification relates to prior forms of ethnic prejudice, discrimination and racism. It thereby also complicates the prominent discussion on the nexus between gentrification and displacement by showing that, even if long-time residents are not immediately threatened with having to leave, they still experience forms of exclusion that are entrenched with already existing structural inequalities.
Ventilator-induced diaphragm dysfunction in critical illness
Authors: Liu Yung-Yang , Li Li-Fu
Published: November 2018

Mechanical ventilation is an essential intervention for intensive care unit patients with acute lung injury. However, the use of controlled mechanical ventilation in both animal and human models causes ventilator-induced diaphragm dysfunction, wherein a substantial reduction in diaphragmatic force-generating capacity occurs, along with structural injury and atrophy of diaphragm muscle fibers. Although diaphragm dysfunction, noted in most mechanically ventilated patients, is correlated with poor clinical outcome, the specific pathophysiology underlying ventilator-induced diaphragm dysfunction requires further elucidation. Numerous factors may underlie this condition in humans as well as animals, such as increased oxidative stress, calcium-activated calpain and caspase-3, the ubiquitin–proteasome system, autophagy–lysosomal pathway, and proapoptotic proteins. All these alter protein synthesis and degradation, thus resulting in muscle atrophy and impaired contractility and compromising oxidative phosphorylation and upregulating glycolysis associated with impaired mitochondrial function. Furthermore, infection combined with mechanical stretch may induce multisystem organ failure and render the diaphragm more sensitive to ventilator-induced diaphragm dysfunction. Herein, several major cellular mechanisms associated with autophagy, apoptosis, and mitochondrial biogenesis—including toll-like receptor 4, nuclear factor-κB, Src, class O of forkhead box, signal transducer and activator of transcription 3, and Janus kinase—are reviewed. In addition, we discuss the potential therapeutic strategies used to ameliorate ventilator-induced diaphragm dysfunction and thus prevent delay in the management of patients under prolonged duration of mechanical ventilation.

Impact statement

Mechanical ventilation (MV) is life-saving for patients with acute respiratory failure but also causes difficult liberation of patients from ventilator due to rapid decrease of diaphragm muscle endurance and strength, which is termed ventilator-induced diaphragmatic damage (VIDD). Numerous studies have revealed that VIDD could increase extubation failure, ICU stay, ICU mortality, and healthcare expenditures. However, the mechanisms of VIDD, potentially involving a multistep process including muscle atrophy, oxidative loads, structural damage, and muscle fiber remodeling, are not fully elucidated. Further research is necessary to unravel mechanistic framework for understanding the molecular mechanisms underlying VIDD, especially mitochondrial dysfunction and increased mitochondrial oxidative stress, and develop better MV strategies, rehabilitative programs, and pharmacologic agents to translate this knowledge into clinical benefits.
Flexible Parametric Alternatives to the Cox Model, and more
Authors: Royston Patrick
Published: November 2018

Since its introduction to a wondering public in 1972, the Cox proportional hazards regression model has become an overwhelmingly popular tool in the analysis of censored survival data. However, some features of the Cox model may cause problems for the analyst or an interpreter of the data. They include the restrictive assumption of proportional hazards for covariate effects, and “loss” (non-estimation) of the baseline hazard function induced by conditioning on event times. In medicine, the hazard function is often of fundamental interest since it represents an important aspect of the time course of the disease in question. In the present article, the Stata implementation of a class of flexible parametric survival models recently proposed by Royston and Parmar (2001) will be described. The models start by assuming either proportional hazards or proportional odds (user-selected option). The baseline distribution function is modeled by restricted cubic regression spline in log time, and parameter estimation is by maximum likelihood. Model selection and choice of knots for the spline function are discussed. Interval-censored data and models in which one or more covariates have nonproportional effects are also supported by the software. Examples based on a study of prognostic factors in breast cancer are given.
Statistical Software Certification
Authors: Gould William
Published: November 2018

In the first part (sections 1 and 2), this article describes the automated process that is used to certify Stata prior to shipment of new releases or updates. The second part (section 3) describes how these techniques can be adopted to your own work.
Speaking Stata: Graphing Distributions
Authors: Cox Nicholas J.
Published: November 2018

Graphing univariate distributions is central to both statistical graphics, in general, and Stata's graphics, in particular. Now that Stata 8 is out, a review of official and user-written commands is timely. The emphasis here is on going beyond what is obviously and readily available, with pointers to minor and major trickery and various user-written commands. For plotting histogram-like displays, kernel-density estimates and plots based on distribution functions or quantile functions, a large variety of choices is now available to the researcher.
Review of Veterinary Epidemiologic Research by Dohoo, Martin, and Stryhn
Authors: Audigé Laurent
Published: November 2018

The new book by Dohoo, Martin, and Stryhn (2003) is reviewed.
Reliable Estimation of Generalized Linear Mixed Models using Adaptive Quadrature
Authors: Rabe-Hesketh Sophia , Skrondal Anders , Pickles Andrew
Published: November 2018

Generalized linear mixed models or multilevel regression models have become increasingly popular. Several methods have been proposed for estimating such models. However, to date there is no single method that can be assumed to work well in all circumstances in terms of both parameter recovery and computational efficiency. Stata's xt commands for two-level generalized linear mixed models (e.g., xtlogit) employ Gauss–Hermite quadrature to evaluate and maximize the marginal log likelihood. The method generally works very well, and often better than common contenders such as MQL and PQL, but there are cases where quadrature performs poorly. Adaptive quadrature has been suggested to overcome these problems in the two-level case. We have recently implemented a multilevel versionofthismethodin gllamm, a program that fits a large class of multilevel latent variable models including multilevel generalized linear mixed models. As far as we know, this is the first time that adaptive quadrature has been proposed for multilevel models. We show that adaptive quadrature works well in problems where ordinary quadrature fails. Furthermore, even when ordinary quadrature works, adaptive quadrature is often computationally more efficient since it requires fewer quadrature points to achieve the same precision.
Parametric Frailty and Shared Frailty Survival Models
Authors: Gutierrez Roberto G.
Published: November 2018

Frailty models are the survival data analog to regression models, which account for heterogeneity and random effects. A frailty is a latent multiplicative effect on the hazard function and is assumed to have unit mean and variance θ, which is estimated along with the other model parameters. A frailty model is an heterogeneity model where the frailties are assumed to be individual- or spell-specific. A shared frailty model is a random effects model where the frailties are common (or shared) among groups of individuals or spells and are randomly distributed across groups. Parametric frailty models were made available in Stata with the release of Stata 7, while parametric shared frailty models were made available in a recent series of updates. This article serves as a primer to those fitting parametric frailty models in Stata via the streg command. Frailty models are compared to shared frailty models, and both are shown to be equivalent in certain situations. The user-specified form of the distribution of the frailties (whether gamma or inverse Gaussian) is shown to subtly affect the interpretation of the results. Methods for obtaining predictions that are either conditional or unconditional on the frailty are discussed. An example that analyzes the time to recurrence of infection after catheter insertion in kidney patients is studied.
From the Help Desk: Transfer Functions
Authors: McDowell Allen
Published: November 2018

The question often arises as to whether one can estimate a transfer function model using Stata. While Stata does not currently have a convenience command for doing so, this article will demonstrate that estimating such a model can be accomplished quite easily using Stata's arima command. The classic text for transfer function modeling is Box, Jenkins, and Reinsel (1994); however, a more concise presentation can be found in Brockwell and Davis (1991).
Power by Simulation
Authors: Feiveson A. H.
Published: November 2018

This paper describes how to write Stata programs to estimate the power of virtually any statistical test that Stata can perform. Examples given include the t test, Poisson regression, Cox regression, and the nonparametric rank-sum test.
G-estimation of Causal Effects, Allowing for Time-varying Confounding
Authors: Sterne Jonathan A. C. , Tilling Kate
Published: November 2018

This article describes the stgest command, which implements G-estimation (as proposed by Robins) to estimate the effect of a time-varying exposure on survival time, allowing for time-varying confounders.
Speaking Stata: How to Face Lists with Fortitude
Authors: Cox Nicholas J.
Published: November 2018

Three commands in official Stata, foreach, forvalues, and for, provide structures for cycling through lists of values (variable names, numbers, arbitrary text) and repeating commands using members of those lists in turn. All these commands may be used interactively, and none is restricted to use in Stata programs. They are explained and compared in some detail with a variety of examples. In addition, a self-contained exposition is given on local macros, understanding of which is needed for use of foreach and forvalues.
The Robust Variance Estimator for Two-stage Models
Authors: Hardin James W.
Published: November 2018

This article discusses estimates of variance for two-stage models. We present the sandwich estimate of variance as an alternative to the Murphy–Topel estimate. The sandwich estimator has a simple formula that is similar to the formula for the Murphy–Topel estimator, and the two estimators are asymptotically equal when the assumed model distributions are true. The advantages of the sandwich estimate of variance are that it may be calculated for the complete parameter vector, and that it requires estimating equations instead of fully specified log likelihoods.
Speaking Stata: On Numbers and Strings
Authors: Cox Nicholas J.
Published: November 2018

The great divide among data types in Stata is between numeric and string variables. Most of the time, which kind you want to use for particular variables is clear and unproblematic, but surprisingly often, users face difficulties in making the right decision or need to convert variables from one kind to another. The main problems that may arise and their possible solutions are surveyed with reference both to official Stata and to user-written programs.
Estimation of Average Treatment Effects Based on Propensity Scores
Authors: Becker Sascha O. , Ichino Andrea
Published: November 2018

In this paper, we give a short overview of some propensity score matching estimators suggested in the evaluation literature, and we provide a set of Stata programs, which we illustrate using the National Supported Work (NSW) demonstration widely known in labor economics.
The Clustergram: A Graph for Visualizing Hierarchical and Nonhierarchical Cluster Analyses
Authors: Schonlau Matthias
Published: November 2018

In hierarchical cluster analysis, dendrograms are used to visualize how clusters are formed. I propose an alternative graph called a “clustergram” to examine how cluster members are assigned to clusters as the number of clusters increases. This graph is useful in exploratory analysis for nonhierarchical clustering algorithms such as k-means and for hierarchical cluster algorithms when the number of observations is large enough to make dendrograms impractical. I present the Stata code and give two examples.
Instrumental Variables and GMM: Estimation and Testing
Authors: Baum Christopher F. , Schaffer Mark E. , Stillman Steven
Published: November 2018

We discuss instrumental variables (IV) estimation in the broader context of the generalized method of moments (GMM), and describe an extended IV estimation routine that provides GMM estimates as well as additional diagnostic tests. Stand-alone test procedures for heteroskedasticity, overidentification, and endogeneity in the IV context are also described.
Sample Size Calculations for Main Effects and Interactions in Case–control Studies using Stata's nchi2 and npnchi2 Functions
Authors: Saunders Catherine L. , Bishop D. Timothy , Barrett Jennifer H.
Published: November 2018

The non-central X2 distribution can be used to calculate power for tests detecting departure from a null hypothesis. Required sample size can also be calculated because it is proportional to the non-centrality parameter for the distribution. We demonstrate how these calculations can be carried out in Stata using the example of calculating power and sample size for case–control studies of gene–gene and gene–environment interactions. Do-files are available for these calculations.
Review of a Short Introduction to Stata for Biostatistics by Hills and De Stavola
Authors: McGready John
Published: November 2018

The new book by Hills and De Stavola (2002) is reviewed.
The Stata Journal so Far: Editors’ Report
Authors: Newton H. Joseph , Cox Nicholas J.
Published: November 2018

The editor and executive editor give some thoughts on the recent past, the present, and the immediate future of the Stata Journal.
Adaptive Kernel Density Estimation
Authors: Van Kerm Philippe
Published: November 2018

This insert describes the module akdensity. akdensity extends the official kdensity that estimates density functions by the kernel method. The extensions are of two types: akdensity allows the use of an “adaptive kernel” approach with varying, rather than fixed, bandwidths; and akdensity estimates pointwise variability bands around the estimated density functions.
Testing for Serial Correlation in Linear Panel-data Models
Authors: Drukker David M.
Published: November 2018

Because serial correlation in linear panel-data models biases the standard errors and causes the results to be less efficient, researchers need to identify serial correlation in the idiosyncratic error term in a panel-data model. A new test for serial correlation in random- or fixed-effects one-way models derived by Wooldridge (2002) is attractive because it can be applied under general conditions and is easy to implement. This paper presents simulation evidence that the new Wooldridge test has good size and power properties in reasonably sized samples.
Do-it-yourself Shuffling and the Number of Runs under Randomness
Authors: Smeeton Nigel , Cox Nicholas J.
Published: November 2018

A common class of problem in statistical science is estimating, as a benchmark, the probability of some event under randomness. For example, in a sequence of events in which several outcomes are possible and the length of the sequence and number of outcomes of each type known, the number of runs gives an indication of whether the outcomes are random, clustered, or alternating. This note explains and illustrates a simple method of random shuffling that is often useful. We show how the conditional probability distribution of the number of runs may be derived easily in Stata, thus yielding p-values for testing the null hypothesis that the type of outcome is random. We also compare our direct approach with that using the simulate command.
From the Help Desk: Swamy's Random-coefficients Model
Authors: Poi Brian P.
Published: November 2018

This article discusses the Swamy (1970) random-coefficients model and presents a command that extends Stata's xtrchh command by also providing estimates of the panel-specific coefficients.
Computing Interaction Effects and Standard Errors in Logit and Probit Models
Authors: Norton Edward C. , Wang Hua , Ai Chunrong
Published: November 2018

This paper explains why computing the marginal effect of a change in two variables is more complicated in nonlinear models than in linear models. The command inteff computes the correct marginal effect of a change in two interacted variables for a logit or probit model, as well as the correct standard errors. The inteff command graphs the interaction effect and saves the results to allow further investigation.
Multiple Imputation of Missing Values
Authors: Royston Patrick
Published: November 2018

Following the seminal publications of Rubin about thirty years ago, statisticians have become increasingly aware of the inadequacy of “complete-case” analysis of datasets with missing observations. In medicine, for example, observations may be missing in a sporadic way for different covariates, and a complete-case analysis may omit as many as half of the available cases. Hotdeck imputation was implemented in Stata in 1999 by Mander and Clayton. However, this technique may perform poorly when many rows of data have at least one missing value. This article describes an implementation for Stata of the MICE method of multiple multivariate imputation described by van Buuren, Boshuizen, and Knook (1999). MICE stands for multivariate imputation by chained equations. The basic idea of data analysis with multiple imputation is to create a small number (e.g., 5–10) of copies of the data, each of which has the missing values suitably imputed, and analyze each complete dataset independently. Estimates of parameters of interest are averaged across the copies to give a single estimate. Standard errors are computed according to the “Rubin rules”, devised to allow for the between- and within-imputation components of variation in the parameter estimates. This article describes five ado-files. mvis creates multiple multivariate imputations. uvis imputes missing values for a single variable as a function of several covariates, each with complete data. micombine fits a wide variety of regression models to a multiply imputed dataset, combining the estimates using Rubin's rules, and supports survival analysis models (stcox and streg), categorical data models, generalized linear models, and more. Finally, misplit and mijoin are utilities to intercon-vert datasets created by mvis and by the miset program from John Carlin and colleagues. The use of the routines is illustrated with an example of prognostic modeling in breast cancer.
Maximum Likelihood Estimation of Endogenous Switching Regression Models
Authors: Lokshin Michael , Sajaia Zurab
Published: November 2018

This article describes the movestay Stata command, which implements the maximum likelihood method to fit the endogenous switching regression model.
Implementing Matching Estimators for Average Treatment Effects in Stata
Authors: Abadie Alberto , Drukker David , Herr Jane Leber , Imbens Guido W.
Published: November 2018

This paper presents an implementation of matching estimators for average treatment effects in Stata. The nnmatch command allows you to estimate the average effect for all units or only for the treated or control units; to choose the number of matches; to specify the distance metric; to select a bias adjustment; and to use heteroskedastic-robust variance estimators.
Simple Thematic Mapping
Authors: Pisati Maurizio
Published: November 2018

Thematic maps illustrate the spatial distribution of one or more variables of interest within a given geographic unit. In a sense, a thematic map is the spatial analyst's equivalent to the scatterplot in nonspatial analysis. This paper presents the tmap package, a set of Stata programs designed to draw five kinds of thematic maps: choropleth, proportional symbol, deviation, dot, and label maps. The first three kinds of maps are intended to depict area data, the fourth is suitable for representing point data, and the fifth can be used to show data of both types.