Working with a net

Networking is a critical skill-set that physicians, as they evolve into management and executive positions, need to develop and utilize. A network is a web of personal and professional connections built up over a lifetime based on mutual interests and nurtured by ongoing regular contacts. Good networkers, most especially those for whom bonhomie is not second nature, pursue the project systematically. They set up a schedule for keeping connections alive, they compile and refresh the network database, they attend forums where old acquaintances can be renewed and new ones formed, they follow a set of best practices, and they arm themselves with the essential instruments of the networking trade (primarily a pencil, a business card, and an open attitude). Successful networking requires the ability to ask for favors--but also to extend them willingly. Networking is an exponential process of harnessing connections to connections--one's own network to those of others, to gain knowledge and elicit opportunities that would otherwise be unavailable.     

Attitudes toward war and peace and their relations with anxiety reactions among adolescents living in a conflictual area

The present study examined attitudes toward war and peace during a violent conflict and their relationships with anxiety reactions. We aimed to find out if attitudes toward the conflict in general or attitudes toward the specific operation are linked to anxiety reactions during a stressful situation and if a personal coping resource mediates the relationships between these attitudes and anxiety. Data were gathered on November 2012 from 78 Jewish adolescents living in southern Israel who were exposed to missile attacks during a military operation. Adolescents filled out self-report questionnaires which included socio-demographic characteristics; attitudes toward the military operation; ways to resolve the Israeli–Palestinian conflict; and sense of coherence and state anxiety. Results showed that most of the adolescents believed that a military operation would diminish the missile attacks to some extent or totally. Overall, adolescents who believed that a military operation would resolve the situation for a limited time were more anxious, while those who believed that it would open the opportunity for negotiation with the enemy, socialization, education, and mutual interest were less anxious. Results are discussed against the background of the meanings of growing up in the shadow of intractable violent conflict.     

The effect of variability and carryover on average bioequivalence assessment: a simulation study

The purpose of this study was to evaluate the effect of residual variability and carryover on average bioequivalence (ABE) studies performed under a 22 crossover design. ABE is usually assessed by means of the confidence interval inclusion principle. Here, the interval under consideration was the standard 'shortest' interval, which is the mainstream approach in practice. The evaluation was performed by means of a simulation study under different combinations of carryover and residual variability besides of formulation effect and sample size. The evaluation was made in terms of percentage of ABE declaration, coverage and interval precision. As is well known, high levels of variability distort the ABE procedures, particularly its type II error control (i.e. high variabilities make difficult to declare bioequivalence when it holds). The effect of carryover is modulated by variability and is especially disturbing for the type I error control. In the presence of carryover, the risk of erroneously declaring bioequivalence may become high, especially for low variabilities and large sample sizes. We end up with some hints concerning the controversy about pretesting for carryover before performing ABE analysis.     

On convergence of the EM algorithmand the Gibbs sampler

In this article we investigate the relationship between the EM algorithm and the Gibbs sampler. We show that the approximate rate of convergence of the Gibbs sampler by Gaussian approximation is equal to that of the corresponding EM-type algorithm. This helps in implementing either of the algorithms as improvement strategies for one algorithm can be directly transported to the other. In particular, by running the EM algorithm we know approximately how many iterations are needed for convergence of the Gibbs sampler. We also obtain a result that under certain conditions, the EM algorithm used for finding the maximum likelihood estimates can be slower to converge than the corresponding Gibbs sampler for Bayesian inference. We illustrate our results in a number of realistic examples all based on the generalized linear mixed models.     

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.