Using a mixture model for multiple imputation in the presence of outliers: the 'Healthy for life' project

Summary.  We consider the problem of obtaining population-based inference in the presence of missing data and outliers in the context of estimating the prevalence of obesity and body mass index measures from the 'Healthy for life' study. Identifying multiple outliers in a multivariate setting is problematic because of problems such as masking, in which groups of outliers inflate the covariance matrix in a fashion that prevents their identification when included, and swamping, in which outliers skew covariances in a fashion that makes non-outlying observations appear to be outliers. We develop a latent class model that assumes that each observation belongs to one of K unobserved latent classes, with each latent class having a distinct covariance matrix. We consider the latent class covariance matrix with the largest determinant to form an 'outlier class'. By separating the covariance matrix for the outliers from the covariance matrices for the remainder of the data, we avoid the problems of masking and swamping. As did Ghosh-Dastidar and Schafer, we use a multiple-imputation approach, which allows us simultaneously to conduct inference after removing cases that appear to be outliers and to promulgate uncertainty in the outlier status through the model inference. We extend the work of Ghosh-Dastidar and Schafer by embedding the outlier class in a larger mixture model, consider penalized likelihood and posterior predictive distributions to assess model choice and model fit, and develop the model in a fashion to account for the complex sample design. We also consider the repeated sampling properties of the multiple imputation removal of outliers.     

Psychosocial stress and job satisfaction in female office employees with and without neck-shoulder symptoms

The objective of this research performed in a Finnish occupational health care setting was to describe the annual prevalence of neck and shoulder symptoms in female office employees and to test whether or not these symptoms were associated with psychosocial stress, job satisfaction and health locus of control. The subjects consisted wholly of female office employees (n = 232) at one local bank and three insurance offices, chosen on a voluntary basis. The annual prevalence of disturbing neck-shoulder symptoms among female office employees was 43.3%. An association of these symptoms with psychosomatic symptoms, poor general job satisfaction and its two subdimensions, work content and perception of the healthiness of the working environment, was noticed. The subjects with neck-shoulder symptoms had a significantly higher score of feelings of external control (fatalism) than those without symptoms. The results lead to the conclusion that neck-shoulder symptoms are common amongst female office employees. These symptoms are associated with some psychosocial stress factors and job dissatisfaction. In future, it would be important to pay attention to these factors when trying to reduce the prevalence of neck-shoulder symptoms in office work.     

Estimation for hidden Markov random fields

A finite state Markov random field is noisily observed via a second finite state process. The parameters of the model are estimated, as well as the most likely signal given the observations.     

A MODEL FOR COLLABORATIVE TEAM PROCESSING IN BRIEF SYSTEMIC FAMILY THERAPY*

While there has been considerable growth in recent years in the use of collaborative teamwork in Systemic Family Therapy, there has been a dearth of literature concerning the process of team functioning. Based upon a careful analysis of actual teamwork, a model for conducting more efficient and effective team conferences has been developed. The ensuing discussion examines the risks in working in teams and proposes ways to counteract these. Further avenues of research are suggested.     

Do Personality Changes Occur in Parents Receiving Behavioral Family Therapy?

The present outcome study is a preliminary report on whether personality changes occur in parents receiving behavioral family therapy. Behavioral techniques for changing the identified patient's presenting problem were taught to the parents and each family member was given a weekly behavioral homework assignment intended to change the dysfunctional interactions assessed in the family.
An analysis of pre and post measures using Cattell's 16PF questionnaire showed a significant decrease in the parent's self-sufficiency index, indicating increased group dependence. The mean number of sessions was 12.6. The results of this study raise questions about the nature of the personality changes occurring in family therapy of this type. Family therapists, often-times assuming the role of the "expert" for the family, may be unwittingly fostering group dependence and losses in confidence for parents receiving such family guidance.     

外国领导是怎么炼成的

具有“个人魅力”的领导人往往能使人对其忠诚,但并不是每个社会都需要一个“个人魅力”型的领导人,在非洲和一些拉美国家,个人魅力甚至会起到负作用。在没有个人魅力的时候,只要你付出更多的努力,也能成为一名优秀的领导人。     

Modelling the travel time of transit vehicles in real‐time through a GTFS‐based road network using GPS vehicle locations

Predicting the arrival time of a transit vehicle involves not only knowledge of its current position and schedule adherence, but also traffic conditions along the remainder of the route. Road networks are dynamic and can quickly change from free‐flowing to highly congested, which impacts the arrival time of transit vehicles, particularly buses which often share the road with other vehicles, so reliable predictions need to account for real‐time and future traffic conditions. The first step in this process is to construct a framework with which road state (traffic conditions) can be estimated using real‐time transit vehicle position data. Our proposed framework implements a vehicle model using a particle filter to estimate road travel times, which are used in a second model to estimate real‐time traffic conditions. Although development and testing took place in Auckland, New Zealand, we generalised each component to make the framework compatible with other public transport systems around the world. We demonstrate the real‐time feasibility and performance of our approach in real‐time, where a combination of R and C++ was used to obtain the necessary performance results. Future work will use these estimated traffic conditions in combination with historical data to obtain reliable arrival time predictions of transit vehicles.     

Diagnostic sequence of cocaine use disorder in relation to other mental health conditions among college students

Abstract

Objective: Cocaine use is increasing. Comorbidities and diagnostic sequencing are needed among college students to inform treatment of cocaine use disorder (CUD). Method: Using electronic medical records from the psychiatric clinic at the student health care center of a large, public university from 2005 to 2015, patients diagnosed with CUD were identified. Their top mental health conditions were identified and assessed to see whether the first diagnosis of these conditions was made (1) before, (2) at the same time as, or (3) after the first diagnosis of CUD. Results: Among the 50 CUD patients, their most common mental health comorbidities were alcohol use disorder, anxiety, depression, and cannabis use disorder. Anxiety and depression were likely to be diagnosed before CUD; alcohol and cannabis use disorders were likely to be diagnosed concurrently with CUD. Conclusion: Diagnostic sequencing can be used to inform screening, workup, and treatment for patients with CUD.