Analysing mark-recapture-recovery data in the presence of missing covariate data via multiple imputation

We consider mark–recapture–recovery data with additional individual time-varying continuous covariate data. For such data it is common to specify the model parameters, and in particular the survival probabilities, as a function of these covariates to incorporate individual heterogeneity. However, an issue arises in relation to missing covariate values, for (at least) the times when an individual is not observed, leading to an analytically intractable likelihood. We propose a two-step multiple imputation approach to obtain estimates of the demographic parameters. Firstly, a model is fitted to only the observed covariate values. Conditional on the fitted covariate model, multiple “complete” datasets are generated (i.e. all missing covariate values are imputed). Secondly, for each complete dataset, a closed form complete data likelihood can be maximised to obtain estimates of the model parameters which are subsequently combined to obtain an overall estimate of the parameters. Associated standard errors and 95 % confidence intervals are obtained using a non-parametric bootstrap. A simulation study is undertaken to assess the performance of the proposed two-step approach. We apply the method to data collected on a well-studied population of Soay sheep and compare the results with a Bayesian data augmentation approach. Supplementary materials accompanying this paper appear on-line.Publisher PDFPeer reviewe

The Welfare Cost of Means-Testing: Pensioner Participation in Income Support

We estimate parametric and semi-parametric binary choice models of benefit take-up by British pensioners and develop methods, based on the compensating variation, of inferring the cash-equivalent value of disutility arising from stigma or complexity of the claims process, taking account of the self-selection induced by take-up. We extend this to incorporate the claim costs borne by welfare-recipients into the measurement of pensioner poverty. We find that allowing for implicit claim costs in this way has a non-negligible impact on poverty measurement.benefit take-up; program participation; pensions; welfare; poverty

The Warwick-Edinburgh Mental Well-being Scale (WEMWBS) : development and UK validation

Background There is increasing international interest in the concept of mental well-being and its contribution to all aspects of human life. Demand for instruments to monitor mental well-being at a population level and evaluate mental health promotion initiatives is growing. This article describes the development and validation of a new scale, comprised only of positively worded items relating to different aspects of positive mental health: the Warwick-Edinburgh Mental Well-Being Scale (WEMWBS). Methods WEMWBS was developed by an expert panel drawing on current academic literature, qualitative research with focus groups, and psychometric testing of an existing scale. It was validated on a student and representative population sample. Content validity was assessed by reviewing the frequency of complete responses and the distribution of responses to each item. Confirmatory factor analysis was used to test the hypothesis that the scale measured a single construct. Internal consistency was assessed using Cronbach's alpha. Criterion validity was explored in terms of correlations between WEMWBS and other scales and by testing whether the scale discriminated between population groups in line with pre-specified hypotheses. Test-retest reliability was assessed at one week using intra-class correlation coefficients. Susceptibility to bias was measured using the Balanced Inventory of Desired Responding. Results WEMWBS showed good content validity. Confirmatory factor analysis supported the single factor hypothesis. A Cronbach's alpha score of 0.89 (student sample) and 0.91 (population sample) suggests some item redundancy in the scale. WEMWBS showed high correlations with other mental health and well-being scales and lower correlations with scales measuring overall health. Its distribution was near normal and the scale did not show ceiling effects in a population sample. It discriminated between population groups in a way that is largely consistent with the results of other population surveys. Test-retest reliability at one week was high (0.83). Social desirability bias was lower or similar to that of other comparable scales. Conclusion WEMWBS is a measure of mental well-being focusing entirely on positive aspects of mental health. As a short and psychometrically robust scale, with no ceiling effects in a population sample, it offers promise as a tool for monitoring mental well-being at a population level. Whilst WEMWBS should appeal to those evaluating mental health promotion initiatives, it is important that the scale's sensitivity to change is established before it is recommended in this context

B_K in Staggered Chiral Perturbation Theory

We calculate the kaon B-parameter, B_K, to next-to-leading order in staggered chiral perturbation theory. We find expressions for partially quenched QCD with three sea quarks, quenched QCD, and full QCD with m_u = m_d but not equal to m_s. We extend the usual power counting to include the effects of using perturbative (rather than non-perturbative) matching factors. Taste breaking enters through the O(a^2) terms in the effective action, through O(a^2) terms from the discretization of operators, and through the truncation of matching factors. These effects cause mixing with several additional operators, complicating the chiral and continuum extrapolations. In addition to the staggered expressions, we present B_K at next-to-leading order in continuum partially quenched chiral perturbation theory for N_f=3 sea quarks with m_u = m_d but not equal to m_s.Comment: 56 pages, 3 figures (v3: Corrected normalization error in Eq.(4) and subsequent equations; physics results unchanged. Version accepted to Phys. Rev. D.

Experts and evidence in deliberation: scrutinising the role of witnesses and evidence in mini-publics, a case study

Experts hold a prominent position in guiding and shaping policy-making; however, the nature of expert input to decision-making is a topic of public debate. A key aspect of deliberative processes such as citizens’ juries is the provision of information to participants, usually from expert witnesses. However, there is currently little guidance on some of the challenges that organisers and advocates of citizens’ juries must consider regarding expert involvement, including the role of the witness, issues around witness identification and selection, the format of evidence provision, the evidence itself, and how these factors affect the experience of the participants and the witnesses. Here, we explore these issues through detailed case study of three citizens’ juries on onshore wind farm development in Scotland, including interviews with the witnesses involved. This is complemented by examining a cohort of mini-publics held on energy and the environment topics, and, where possible, discussion with the program organisers. We identify a series of issues and sensitivities that can compromise the effectiveness and fairness of the evidence-giving in mini-publics, for the participants, the witnesses and the organisers. We recommend approaches and areas for future work to address these challenges. This is the first time that the ways of involving witnesses in such processes have been so comprehensively examined, and is timely given the increasing interest in democratic innovations such as mini-publics and the current discourse concerning experts

P2X receptor trafficking in neurons is subunit specific

P2X receptors within the CNS mediate excitatory synaptic transmission and also act presynaptically to modulate neurotransmitter release. We have studied the targeting and trafficking of P2X4 and P2X2 receptors heterologously expressed in cultured olfactory bulb neurons. Homomeric P2X4 receptors had a punctate distribution, and many of the puncta colocalized with early endosomes. In contrast, P2X2 receptors were primarily localized at the plasma membrane. By antibody-labeling of surface receptors in living neurons, we showed that P2X4 receptors undergo rapid constitutive internalization and subsequent reinsertion into the plasma membrane, whereas P2X2 receptors were not regulated in such a way. The internalization of P2X4 receptors was dynamin-dependent, and the binding of ATP enhanced the basal rate of retrieval in a Ca2+-independent manner. The presence of the P2X4 subunit in a P2X4/6 heteromer governed the trafficking properties of the receptor. P2X receptors acted presynaptically to enhance the release of glutamate, suggesting that the regulated cycling of P2X4-containing receptors might provide a mechanism for modulation of synaptic transmission

The distributional impact of reforms to disability benefits for older people in the UK

The UK Attendance Allowance (AA) and Disability Living Allowance (DLA) are non means-tested benefits paid to many disabled people aged 65+. They may also increase entitlements to means-tested benefits through the Severe Disability Premium (SDP). We investigate proposed reforms involving withdrawal of AA/DLA. Despite their present non-means-tested nature, we show that withdrawal would affect mainly low-income people, whose losses could be mitigated if SDP were retained at its current or a higher level. We also show the importance of the method of describing distributional impacts and that use of inappropriate income definitions in official reports has overstated recipients' capacity to absorb the loss of these benefits