A new alternative to the standard F test for clustered data

The data collection process and the inherent population structure are the main causes for clustered data. The observations in a given cluster are correlated, and the magnitude of such correlation is often measured by the intra-cluster correlation coefficient. The intra-cluster correlation can lead to an inflated size of the standard F test in a linear model. In this paper, we propose a solution to this problem. Unlike previous adjustments, our method does not require estimation of the intra-class correlation, which is problematic especially when the number of clusters is small. Our simulation results show that the new method outperforms the existing methods.     

ESTIMATING A PARAMETER WHEN IT IS KNOWN THAT THE PARAMETER EXCEEDS A GIVEN VALUE

In some statistical problems a degree of explicit, prior information is available about the value taken by the parameter of interest, θ say, although the information is much less than would be needed to place a prior density on the parameter's distribution. Often the prior information takes the form of a simple bound, ‘θ > θ₁ ’ or ‘θ < θ₁ ’, where θ₁ is determined by physical considerations or mathematical theory, such as positivity of a variance. A conventional approach to accommodating the requirement that θ > θ₁ is to replace an estimator, , of θ by the maximum of and θ₁. However, this technique is generally inadequate. For one thing, it does not respect the strictness of the inequality θ > θ₁ , which can be critical in interpreting results. For another, it produces an estimator that does not respond in a natural way to perturbations of the data. In this paper we suggest an alternative approach, in which bootstrap aggregation, or bagging, is used to overcome these difficulties. Bagging gives estimators that, when subjected to the constraint θ > θ₁ , strictly exceed θ₁ except in extreme settings in which the empirical evidence strongly contradicts the constraint. Bagging also reduces estimator variability in the important case for which is close to θ₁, and more generally produces estimators that respect the constraint in a smooth, realistic fashion.     

A simple two-stage design for quantitative responses with application to a study in diabetic neuropathic pain

Two-stage designs offer substantial advantages for early phase II studies. The interim analysis following the first stage allows the study to be stopped for futility, or more positively, it might lead to early progression to the trials needed for late phase II and phase III. If the study is to continue to its second stage, then there is an opportunity for a revision of the total sample size. Two-stage designs have been implemented widely in oncology studies in which there is a single treatment arm and patient responses are binary. In this paper the case of two-arm comparative studies in which responses are quantitative is considered. This setting is common in therapeutic areas other than oncology. It will be assumed that observations are normally distributed, but that there is some doubt concerning their standard deviation, motivating the need for sample size review. The work reported has been motivated by a study in diabetic neuropathic pain, and the development of the design for that trial is described in detail.     

Models for the analysis of C-reactive protein in statin trials

Elevation in C-reactive protein (CRP) is an independent risk factor for cardiovascular disease progression and levels are reduced by treatment with statins. However, on-treatment CRP, given baseline CRP and treatment, is not normally distributed and outliers exist even when transformations are applied. Although classical non-parametric tests address some of these issues, they do not enable straightforward inclusion of covariate information. The aims of this study were to produce a model that improved efficiency and accuracy of analysis of CRP data. Estimation of treatment effects and identification of outliers were addressed using controlled trials of rosuvastatin. The robust statistical technique of MM-estimation was used to fit models to data in the presence of outliers and was compared with least-squares estimation. To develop the model, appropriate transformations of the response and baseline variables were selected. The model was used to investigate how on-treatment CRP related to baseline CRP and estimated treatment effects with rosuvastatin. On comparing least-squares and MM-estimation, MM-estimation was superior to least-squares estimation in that parameter estimates were more efficient and outliers were clearly identified. Relative reductions in CRP were higher at higher baseline CRP levels. There was also evidence of a dose-response relationship between CRP reductions from baseline and rosuvastatin. Several large outliers were identified, although there did not appear to be any relationships between the incidence of outliers and treatments. In conclusion, using robust estimation to model CRP data is superior to least-squares estimation and non-parametric tests in terms of efficiency, outlier identification and the ability to include covariate information.     

Missing item imputation for quality-of-life instruments with application to asthma quality-of-life questionnaires

There has been increasing use of quality-of-life (QoL) instruments in drug development. Missing item values often occur in QoL data. A common approach to solve this problem is to impute the missing values before scoring. Several imputation procedures, such as imputing with the most correlated item and imputing with a row/column model or an item response model, have been proposed. We examine these procedures using data from two clinical trials, in which the original asthma quality-of-life questionnaire (AQLQ) and the miniAQLQ were used. We propose two modifications to existing procedures: truncating the imputed values to eliminate outliers and using the proportional odds model as the item response model for imputation. We also propose a novel imputation method based on a semi-parametric beta regression so that the imputed value is always in the correct range and illustrate how this approach can easily be implemented in commonly used statistical software. To compare these approaches, we deleted 5% of item values in the data according to three different missingness mechanisms, imputed them using these approaches and compared the imputed values with the true values. Our comparison showed that the row/column-model-based imputation with truncation generally performed better, whereas our new approach had better performance under a number scenarios.     

The state and the development of an information society: Greek policy and experience

The paper looks into the dynamics of information society policy and its implementation in the Greek context. It argues that information society development is a contested process, influenced by pre‐existing state, economy and society relations. Based on this, it looks into the different aspects of the idiosyncratic path which the evolution of the Greek information society has followed, particularly after 2000. Using Bob Jessop's strategic‐relational approach (SRA) to the state as an analytical framework and drawing on a number of in‐depth interviews with relevant political actors, it provides insights into policy implementation by examining: the public management of information technology projects, how such projects were received in bureaucratic structures and practices, as well as the relationship between the state and the information and communication technology (ICT) sector in public procurement processes. The emphasis is on the period 2000–2008, during which a major operational programme on the information society in Greece was put into effect. The paper also touches upon the post‐2008 experience, suggesting that information society developments might include dynamics operating independently and even in contradiction to the state agenda.     

Is ethnic prejudice declining in Britain? Change in social distance attitudes among ethnic majority and minority Britons

Most literature on racial prejudice deals with the racial attitudes of the ethnic majority and ethnic minorities separately. This paper breaks this tradition. We examine the social distance attitudes of white and non‐white British residents to test if these attitudes follow the same trends over time, whether they are driven by the same social processes and whether they are inter‐related. We have three main findings. Firstly, social distance from other ethnic groups has declined over time for both white and ethnic minority Britons. For the white majority there are both period and cohort elements to this decline. Secondly, we see some evidence that social distance between the majority and minority groups is reciprocal. Specifically, minorities who experience rejection by the white British feel a greater sense of distance from them. Thirdly, we find that all groups share the perception of the same ethnic hierarchy. We see evidence of particularly widespread hostility towards Muslim Britons from all ethnic groups suggesting that Muslims are singled out for negative attention from many British residents of all other backgrounds, including a large number who do not express hostility to other groups.     

Occupational Sex Composition and Gendered Housework Performance: Compensation or Conventionality?

This article examines the association between occupational sex composition and housework, considering total housework time, time on male‐typed and female‐typed tasks, and the percent of total time spent on male and female tasks. Previous research examining male‐ and female‐typed chores independent of total housework suggests that couples compensate for gender‐atypical employment through gender‐typical housework performance, but this analysis of the National Survey of Families and Households (1992–1994) and the American Time Use Survey (2003–2013) demonstrates that assuming a quadratic association and failing to contextualize gendered housework performance within total housework performance obscures the true relationship between occupation and housework. In fact, women and men in gender‐atypical occupations perform a more gender‐atypical combination of chores. The influence of gender deviance neutralization in the housework literature may overshadow alternative explanations and model specifications. In particular, by assuming a quadratic association, researchers may impose, rather than test, gender deviance neutralization.     

Parents at‐risk and their children: intersections of gender role attitudes and parenting practices

Existing research demonstrates that parent and child gender may influence important aspects of family relationships; however, most research in this area has been conducted with non‐clinical samples. As clinicians, it is important to consider how gender impacts family relationships, particularly among vulnerable families. This study examined the intersections of gender role attitudes and parenting practices among 34 parents involved with the child welfare system and referred for clinical intervention. Using a mixed methods design, themes regarding gender role beliefs and parenting practices were found through qualitative interviews with parents. Findings suggested that fathers felt responsible for financially providing for their families and expressed challenges in communicating with mothers, and mothers described challenges they face because of a lack of father involvement. Parents also discussed a perceived need to monitor daughters closely while fostering the independence of their sons. Results of the qualitative analyses were supported by quantitative findings indicating significant differences in harsh and inconsistent discipline practices and clear expectations for girls compared to boys. The discussion addresses implications for clinicians, including how a feminist family therapy perspective may help promote client influence over traditional gender norms by questioning gender role attitudes and exploring alternate narratives that may impact family dynamics.     

Less than human: a qualitative study into the experience of parents involved in the child protection system

This paper reports on the findings from a qualitative study into the experiences of parents who were involved in the English child protection system in 2013. Seventeen in‐depth interviews were conducted involving 19 parents and/or partners, and a framework approach was used to analyse the data. There were positive experiences of individual social workers and some positive experiences of the child protection system. However, the overwhelming theme of the parents' experiences was that the system was uncaring, inflexible and for some harmful to both themselves and their children. Despite being included in the child protection process, parents felt they were not afforded the same rights as a participant, as a decision‐maker or as a partner in seeking to improve the situation. The threat of consequences silenced parents who felt unable to speak out or challenge the things they disagreed with or coerced others into signing agreements they did not agree to. Such experiences related to a sense that they were being treated as ‘less than human’. These findings are considered within the context of recent reforms within the English child protection system.