Residuals for log-Burr XII regression models in survival analysis

In this paper, we compare three residuals to assess departures from the error assumptions as well as to detect outlying observations in log-Burr XII regression models with censored observations. These residuals can also be used for the log-logistic regression model, which is a special case of the log-Burr XII regression model. For different parameter settings, sample sizes and censoring percentages, various simulation studies are performed and the empirical distribution of each residual is displayed and compared with the standard normal distribution. These studies suggest that the residual analysis usually performed in normal linear regression models can be straightforwardly extended to the modified martingale-type residual in log-Burr XII regression models with censored data.     

Likelihood‐based inference for correlated diffusions

The authors address the problem of likelihood‐based inference for correlated diffusions. Such a task presents two issues; the positive definite constraints of the diffusion matrix and the likelihood intractability. The first issue is handled by using the Cholesky factorization on the diffusion matrix. To deal with the likelihood unavailability, a generalization of the data augmentation framework of Roberts and Stramer [Roberts and Stramer (2001) Biometrika 88(3), 603–621] to d‐dimensional correlated diffusions, including multivariate stochastic volatility models, is given. The methodology is illustrated through simulated and real data sets. The Canadian Journal of Statistics 39: 52–72; 2011 © 2011 Statistical Society of Canada     

The Consequences of the Tajikistani Civil War for Abortion and Miscarriage

Although a great deal of attention is paid to reproductive health during violent conflicts, the literature is sparse on the consequences of conflict for abortion and miscarriage. This research provides an analysis of a recent historical case: the 1992–1997 civil war in Tajikistan, using the female questionnaire of the 2007 Tajik Living Standards Survey to examine a subsample of 1445 women surveyed who had reached menarche during or after the war and had been pregnant at least once by the time of the survey. The analysis leverages the uneven geographical scope of conflict events during the civil war to pinpoint women’s exposure to violence, measured by the Uppsala Conflict Data Program. The results show that for women who had reached menarche during or after the civil war, exposure to conflict events increases the likelihood of ever experiencing miscarriage, but not abortion. Including a spatial lag operator reveals that there were also spillover effects for abortion, in which women who were in a broader region of uncertainty were more likely to induce an abortion. These findings highlight the role of institutional changes in affecting pregnancy loss during and after civil war.

     

Estimating stage occupation probabilities in non-Markov models

We study non-Markov multistage models under dependent censoring regarding estimation of stage occupation probabilities. The individual transition and censoring mechanisms are linked together through covariate processes that affect both the transition intensities and the censoring hazard for the corresponding subjects. In order to adjust for the dependent censoring, an additive hazard regression model is applied to the censoring times, and all observed counting and “at risk” processes are subsequently given an inverse probability of censoring weighted form. We examine the bias of the Datta–Satten and Aalen–Johansen estimators of stage occupation probability, and also consider the variability of these estimators by studying their estimated standard errors and mean squared errors. Results from different simulation studies of frailty models indicate that the Datta–Satten estimator is approximately unbiased, whereas the Aalen–Johansen estimator either under- or overestimates the stage occupation probability due to the dependent nature of the censoring process. However, in our simulations, the mean squared error of the latter estimator tends to be slightly smaller than that of the former estimator. Studies on development of nephropathy among diabetics and on blood platelet recovery among bone marrow transplant patients are used as demonstrations on how the two estimation methods work in practice. Our analyses show that the Datta–Satten estimator performs well in estimating stage occupation probability, but that the censoring mechanism has to be quite selective before a deviation from the Aalen-Johansen estimator is of practical importance. N. Gunnes—Supported by a grant from the Norwegian Cancer Society.     

Addressing Psychosocial Barriers to Hospital Discharge: A Social Work Led Model of Care

Australian hospitals regularly care for patients who cannot be discharged routinely due to complex psychosocial needs that manifest as barriers to discharge. These long-stay or “stranded” patients are at risk of detrimental health outcomes resulting from their extended stay while also potentially delaying admission for those who need acute care. This article discusses a new social work led model of care developed at an Australian metropolitan hospital that targets long-stay patients with psychosocial barriers to discharge. The model of care, overseen by a specialist social worker and assistant, demonstrates how the social work profession can take leadership within the psychosocial realm to improve both organisational and patient outcomes.     

Second‐order analysis of marked inhomogeneous spatiotemporal point processes: Applications to earthquake data

To analyze interactions in marked spatiotemporal point processes (MSTPPs), we introduce marked second‐order reduced moment measures and K‐functions for inhomogeneous second‐order intensity‐reweighted stationary MSTPPs. These summary statistics, which allow us to quantify dependence between different mark‐based classifications of points, depend on the specific mark space and mark reference measure chosen. Unbiased and consistent minus‐sampling estimators are derived for all statistics considered, and a test for random labeling is indicated. In addition, we treat Voronoi intensity estimators for MSTPPs. These new statistics are finally employed to analyze an Andaman Sea earthquake data set.     

A Dyadic Perspective on Childhood Maltreatment for Women With Provoked Vestibulodynia and Their Partners: Associations With Pain and Sexual and Psychosocial Functioning

Childhood maltreatment is robustly associated with adult-onset vulvodynia, a common form of female genito-pelvic pain/penetration disorder. However, little is known about the impact of childhood maltreatment on current sexual, psychological, and relationship adaptation for couples with provoked vestibulodynia (PVD). This study examined the associations between childhood maltreatment and sexual and psychosocial functioning and pain in women with PVD, the most common subtype of vulvodynia, and their partners. A total of 49 couples (M_age women = 27.80, SD = 6.05; M_age men = 30.04; SD = 6.48) with PVD completed the Childhood Trauma Questionnaire (CTQ), as well as measures of sexual functioning, couple satisfaction, and anxiety. Women also reported on their pain during intercourse. Analyses were guided by the actor–partner interdependence model. Women’s higher reports of childhood maltreatment were associated with their lower sexual functioning and higher anxiety. Partners’ higher reports of childhood maltreatment were associated with their lower sexual functioning, lower couple satisfaction, and higher anxiety, as well as women’s lower couple satisfaction and higher anxiety. Both women’s and partners’ higher reports of childhood maltreatment were associated with higher affective pain for women. Findings suggest childhood maltreatment experienced by women with PVD and their partners should be considered as part of treatment planning.