Kevin D. Bird

Pathways from War Trauma to Posttraumatic Stress Symptoms Among Tamil Asylum Seekers, Refugees, and Immigrants

Path analysis was used to examine the antecedents of posttraumatic stress (PTS) symptoms in Tamil asylum-seekers, refugees, and immigrants in Australia. The Harvard Trauma Questionnaire and a postmigration living difficulties questionnaire were completed by 62 asylum-seekers, 30 refugees, and 104 immigrants who responded to a mail-out. Demographic characteristics, residency status, and measures of trauma and postmigration stress were fitted to a structural model in PTS symptoms. Premigration trauma exposure accounted for 20% of the variance of PTS symptoms. Postmigration stress contributed 14% of the variance. Although limited by sampling constraints and retrospective measurement, the study supports the notion that both traumatic and posttraumatic events contribute to the expression of PTS symptoms.

Can the chronic fatigue syndrome be defined by distinct clinical features

To determine whether patients diagnosed as having chronic fatigue syndrome (CFS) constitute a clinically homogeneous class, multivariate statistical analyses were used to derive symptom patterns and potential patient subclasses in 565 patients. The notion that patients currently diagnosed as having CFS constitute a single homogeneous class was rejected. An alternative set of clinical subgroups was derived. The validity of these subgroups was assessed by sociodemographic, psychiatric, immunological and illness behaviour variables. A two-class statistical solution was considered most coherent, with patients from the smaller class (27% of the sample) having clinical characteristics suggestive of somatoform disorders. The larger class (73% of sample) presented a more limited combination of fatigue and neuropsychological symptoms, and only moderate disability but remained heterogeneous clinically. The two patient groups differed with regard to duration of illness, spontaneous recovery, severity of current psychological morbidity, utilization of medical services and CD8 T cell subset counts. The distribution of symptoms among patients was not unimodal, supporting the notion that differences between the proposed subclasses were not due simply to differences in symptom severity. This study demonstrated clinical heterogeneity among patients currently diagnosed as CFS, suggesting aetiological heterogeneity. In the absence of discriminative clinical features, current consensus criteria do not necessarily reduce the heterogeneity of patients recruited to CFS research studies.

A comparison of two structured diagnostic interviews: CIDI and SCAN

The relationship between and the inter-rater reliability of the Composite International Diagnostic Interview (CIDI) and the Schedules for Clinical Assessment in Neuropsychiatry (SCAN) for anxiety and depressive disorders were explored. The CIDI and the SCAN were administered by trained interviewers in counterbalanced order. A subsample of interviews was observed to determine the inter-rater reliability of the instruments. Subjects were 101 patients accepted for treatment at an Anxiety Disorders Clinic; 29 of the 101 patients participated in the inter-rater reliability study. Concordance between the instruments as measured by canonical correlation analysis was moderate for current (r=0.69, p=0.05) and for lifetime (r=0.66, p=0.05) diagnoses. Inter-rater reliability of the CIDI was perfect (overall intraclass kappa = 1.00), and of the SCAN was good (overall intraclass kappa = 0.67). It is concluded that although the two instruments made similar diagnostic distinctions, the clinical judgement involved in administering the SCAN resulted in the more moderate levels of agreement between the interviewer and observer than those found for the CIDI.

A computerized harm minimization prevention program for alcohol misuse and related harms: Randomized controlled trial

AIMS Hazardous alcohol use is a leading cause of death among adolescents and young adults world-wide, yet few effective prevention interventions exist. This study was the first to examine a computerized harm minimization intervention to reduce alcohol misuse and related harms in adolescents. DESIGN Cluster randomized controlled trial of a six-session curriculum-integrated harm minimization prevention program. The intervention was delivered by computer in the form of a teenage drama, which provided education through alcohol-related scenarios to which young people could relate. SETTING Schools in Australia. PARTICIPANTS A total of 1466 year 8 students (13 years) from 16 high schools in Australia were allocated randomly to a computerized prevention program (n = 611, eight schools) or usual classes (n = 855, eight schools). MEASUREMENTS Change in knowledge, alcohol use, alcohol-related harms and alcohol expectancies. FINDINGS A computerized prevention program was more effective than usual classes in increasing alcohol-related knowledge of facts that would inform safer drinking choices and decreasing the positive social expectations which students believed alcohol may afford. For females it was effective in decreasing average alcohol consumption, alcohol-related harms and the frequency of drinking to excess (more than four standard drinks; 10 g ethanol). For males the behavioural effects were not significant. CONCLUSIONS A harm minimization approach is effective in educating young people about alcohol-related risks and is effective in reducing risky drinking and harms among girls. Reduction of problems among boys remains a challenge.

Confidence Intervals for Effect Sizes in Analysis of Variance

Although confidence interval procedures for analysis of variance (ANOVA) have been available for some time, they are not well known and are often difficult to implement with statistical packages. This article discusses procedures for constructing individual and simultaneous confidence intervals on contrasts on parameters of a number of fixed-effects ANOVA models, including multivariate analysis of variance (MANOVA) models for the analysis of repeated measures data. Examples show how these procedures can be implemented with accessible software. Confidence interval inference on parameters of random-effects models is also discussed.

Analysis of variance via confidence intervals

Comparing Two Means One-Way Analysis of Variance Precision and Power Simple Factorial Designs Complex Factorial Designs Within-Subjects Designs Mixed Designs

The Problem of Multiple Inference in Psychiatric Research

This paper deals with the problem of multiple inference in psychiatric research, an issue which arises whenever a researcher has to make more than one statistical inference in a single research study. It frequently arises in psychiatric research because of multivariate study designs, with subjects being measured on more than one dependent variable with the intention of studying differences between groups in mean scores. The disadvantages of the commonly adopted strategy of using multiple univariate tests (e.g. multiple t-tests) are outlined. Two broad strategies — Bonferroni-adjusted univariate tests and multivariate statistical analysis — are introduced. Their advantages and disadvantages are discussed in terms of their usefulness in confirmatory and exploratory research in psychiatry.

Simultaneous Test Procedures and the Choice of a Test Statistic in MANOVA

Problems associated with the use of a preliminary multivariate analysis of variance (MANOVA) test in conjunction with univariate follow-up tests can be avoided if follow-up tests are carried out with a simultaneous test procedure (STP) derived from the MANOVA test statistic used for the overall test. It is argued that the choice of a MANOVA test statistic for such analyses should be based on the power and robustness of MANOVA STPS rather than on the properties of the corresponding overall tests. Monte Carlo data are presented which show that the STP based on the trace statistic V can be extremely conservative relative to the STP based on the largest root statistic R. The data suggest that the lack of robustness of the R statistic is unlikely to produce problems if the R STP is used to evaluate interpretable contrasts on linear combinations of variates of interest to the experimenter as opposed to contrasts for which coefficients referring to groups and variates are determined by the data. • When multivariate analysis of variance (MANOVA) is applied to data from a k group experiment (k > 2) with p dependent variables (p> 1), the analysis is usually regarded as a two-stage procedure. Initially an overall test of a general null hypothesis is carried out using one of the various MANOVA test statistics. If, and only if, this general hypothesis is rejected, follow-up tests are carried out in order to clarify the nature of the differences between groups. The properties of MANOVA test statistics and the properties of multiple comparison procedures for follow-up tests are usually treated as unrelated questions. Recent discussions of MANOVA test statistics, for example, make no reference to follow-up tests (Olson, 1974, 1976, 1979; Stevens, 1979). The commonly recommended practice of changing from a multivariate to a univariate test statistic for follow-up tests (Bock, 1975; Finn, 1974; Hummel & Sligo, 1971) is based on the assumptions that the only function of the initial overall test is to protect the second stage of analysis from inflation of the Type I error rate and that the efficiency of this protection does not depend in any way on the nature of the follow-up tests. As Ram

Statistical Power in Psychiatric Research

Statistical power is neglected in much psychiatric research, with the consequence that many studies do not provide a reasonable chance of detecting differences between groups if they exist in the population. This paper attempts to improve current practice by providing an introduction to the essential quantities required for performing a power analysis (sample size, effect size, type 1 and type 2 error rates). We provide simplified tables for estimating the sample size required to detect a specified size of effect with a type 1 error rate of α and a type 2 error rate of β, and for estimating the power provided by a given sample size for detecting a specified size of effect with a type 1 error rate of α. We show how to modify these tables to perform power analyses for multiple comparisons in univariate and some multivariate designs. Power analyses for each of these types of design are illustrated by examples.

Complexity in the relationships among the subdimensions of extraversion and job performance in managerial occupations

The present study investigated differential relationships, nonlinear relationships, and multiplicative relationships among the subdimensions of extraversion (agency and affiliation) and job performance (getting ahead and getting along) for a sample of 179 managers. We found that: (i) agency was positively related to getting ahead performance, whereas affiliation was unrelated to getting ahead; (ii) agency had an inverted-U relationship with getting along performance; and (iii) there was a multiplicative effect of agency and affiliation on getting along. The findings provide insight into the nature of the relationship between extraversion and managerial performance, the level of breadth at which to represent these variables for optimal prediction and explanation, and the use of extraversion measures for selection purposes.