Statistical power in complex experimental designs

We show that power and sample size tables developed by Cohen (1988, pp. 289–354, 381–389) produce incorrect estimates for factorial designs: power is underestimated, and sample size is overestimated. The source of this bias is shrinkage in the implied value of the noncentrality parameter, λ, caused by using Cohen’s adjustment ton for factorial designs (pp. 365 and 396). The adjustment was intended to compensate for differences in the actual versus presumed (by the tables) error degrees of freedom; however, more accurate estimates are obtained if the tables are used without adjustment. The problems with Cohen’s procedure were discovered while testing subroutines in DATASIM 1.2 for computing power and sample size in completely randomized, randomized-blocks, and split-plot factorial designs. The subroutines give the user the ability to generate power and sample size tables that are as easy to use as Cohen’s, but that eliminate the conservative bias of his tables. We also implemented several improvements relative to “manual” use of Cohen’s tables: (1) Since the user can control the specific values of 1- β,n, andf used on the rows and columns of the table, interpolation is never required; (2) exact as opposed to approximate solutions for the noncentralF distribution are employed; (3) solutions for factorial designs, including those with repeated measures factors, take into account the actual error degrees of freedom for the effect being tested; and (4) provision is made for the computation of power for applications involving the doubly noncentralF distribution.     

Reproduction of musical rhythms by children,adult musicians,and adult nonmusicians

Many sequential events, musical rhythms in particular, can be described by a hierarchical structure, with lower order events recursively combining to form higher levels. This study investigated factors influencing the ease of reproduction of short musical rhythms that reflect various organizational principles. For adults and children, reproduction was better for rhythms with the following characteristics: (1) binary rather than ternary subdivision, (2) two rather than three different durations, (3) the ability to be segmented into two shorter rhythms of identical duration, and (4) intensity accents on important hierarchical positions. These findings suggest that a prototypical temporal structure—that is, a regular beat with binary subdivisions—is functional in childhood. The ability to process complex hierarchical structure appeared to be influenced more by musical training than by passive acculturation.     

Induced lateral orientation and persuasibility

It was hypothesized from three different lines of evidence that relative activation of the left cerebral hemisphere of right-handers would increase resistance to a persuasive message as compared to relative activation of the right hemisphere. An experiment was performed using 22 subjects who heard the counterattitudinal message in only one ear and filled in response measures while their body was turned toward that same side. Subjects who listened and turned toward the left agreed more with the views of the message (p less than .05) and produced more thought favorable to the message (p less than .05) than those induced to orient rightward. It was concluded that these results may be due to asymmetries in selective attention, counterarguing, consistency, self-awareness, and perseveration between the cerebral hemispheres of the normal human brain.     

Family Factors in the Development, Treatment, and Prevention of Childhood Anxiety Disorders

It is now widely accepted that anxiety disorders run in families, and current etiological models have proposed both genetic and environmental pathways to anxiety development. In this paper, the familial role in the development, treatment, and prevention of anxiety disorders in children is reviewed. We focus on three anxiety disorders in youth, namely, generalized, separation, and social anxiety as they often co-occur both at the symptom and disorder level and respond to similar treatments. We begin by presenting an overview of a broad range of family factors associated with anxiety disorders. Findings from these studies have informed intervention and prevention strategies that are discussed next. Throughout the paper we shed light on the challenges that plague this research and look toward the future by proposing directions for much needed study and discussing factors that may improve clinical practice and outcomes for affected youth and their families.     

Preventing Maltreatment with a Community-Based Implementation of Parent–Child Interaction Therapy

The purpose of this study was to examine rates of child abuse and neglect reports following a community implementation of Parent–Child Interaction Therapy (PCIT), an evidence-supported intervention for the prevention of maltreatment. Among a group of families receiving PCIT, predictors of reports were examined including family demographics, course of treatment, changes in clinical measures, and caregiver report for prior maltreatment victimization and perpetration. Participants (n = 120) included families at-risk for future maltreatment with and without prior maltreatment history. Agency case records were linked with state administrative records of child welfare reports. Time to follow-up ranged from 13 to 40 months. Bivariate and multivariate survival analyses were used to model risk for a later report. During the follow-up period, 12.5 % of families had a report for physical abuse or neglect. Reports of prior victimization as a child and prior perpetration as an adult were strong predictors of a report of perpetration after PCIT. Dosage of PCIT and change in clinical measures did not increase risk for a later report. PCIT can be an effective intervention for preventing maltreatment. Family history of child welfare involvement is a prominent factor in assessing risk for future involvement.     

Treatment of Posttraumatic Stress Disorder Following an Armed Robbery: A Case Study Testing the Transportability of Trauma-Focused Cognitive-Behavioural Therapy to Urban Africans

John, an urban African male who developed posttraumatic stress disorder (PTSD) following an armed robbery at the petrol station where he worked, was treated with 12 sessions of Trauma-focused cognitive behaviour therapy. Intervention involved a combination of psychoeducation, prolonged imaginal exposure, cognitive restructuring and behavioural assignments. This article is a systematic case study of his treatment which included a comprehensive narrative and tracking of progress by means of the Posttraumatic Diagnostic Scale. John responded well to the treatment, finding it acceptable and credible and remained free of PTSD symptoms at 15 months follow up. It is argued, based on the principles of Elliott's Hermeneutic Single Case Efficacy Design, that there is evidence from within the narrative that it was the treatment that led to remission of symptoms. This case study demonstrates the cognitive, emotional and behavioural processes underlying John's PTSD, which fits with those extensively described in the research literature, and that this evidence-based treatment developed in a westernised context is transportable to work with urban Africans.     

The QCAE: A Questionnaire of Cognitive and Affective Empathy

Empathy has been inconsistently defined and inadequately measured. This research aimed to produce a new and rigorously developed questionnaire. Exploratory (n ₁= 640) and confirmatory (n ₂= 318) factor analyses were employed to develop the Questionnaire of Cognitive and Affective Empathy (QCAE). Principal components analysis revealed 5 factors (31 items). Confirmatory factor analysis confirmed this structure in an independent sample. The hypothesized 2-factor structure (cognitive and affective empathy) was tested and provided the best and most parsimonious fit to the data. Gender differences, convergent validity, and construct validity were examined. The QCAE is a valid tool for assessing cognitive and affective empathy.     

The culture‐negotiation link.

Scholars have only recently begun to assess the strength with which culture affects negotiator communication, as compared with contextual or structural features of business negotiations. Although prior studies reveal important cross‐cultural differences in national negotiating style, they may not help us understand intercultural (mixed‐culture) settings. The crucial question is how heavily are international negotiators influenced by their own cultural values? When negotiating with a culturally disparate partner, what are the separate and cumulative effects of culture and contextual variables on negotiator communication? To answer these questions, the effect of culture (here, individualism‐collectivism) on integrative (information exchange) and distributive (fixed‐sum errors) negotiating is assessed in 32 intercultural dyads. In addition, the contextual effects of role (buyer vs. seller), preconceptions about negotiating (anticipated competition), and mutual adaptation (interdependence in information exchange) are examined. Preliminary results suggest that role requirements influence negotiators more heavily than culture. Supplemental analyses point to some potentially interesting buyer‐seller differences and suggest that information exchange is more a function of reciprocity than of cultural values.     

Child Anxiety Sensitivity and Family Environment as Mediators of the Relationship between Parent Psychopathology, Parent Anxiety Sensitivity, and Child Anxiety

This study examined child anxiety sensitivity and family environment as mediators of the relationship between (1) parent psychopathology and anxiety sensitivity and (2) child anxiety in a community sample of 157 youths aged 7–18 years. Parents completed measures of anxiety sensitivity, psychopathology, and family environment. Youths completed measures of anxiety sensitivity and anxiety. One structural equation model was tested with child anxiety sensitivity as a mediator of (1) parent psychopathology and parent anxiety sensitivity and (2) child anxiety. Mediation was found with respect to parent psychopathology but not anxiety sensitivity. A second structural equation model was tested with family environment (conflict and control) as a mediator of (1) parent psychopathology and parent anxiety sensitivity and (2) child anxiety. Mediation was found with respect to parent psychopathology and anxiety sensitivity. Possible explanations for these pathways are discussed, including information transmission from parents to children, modeling anxiety-based reactions, temperament, and isolation of children from anxiety-provoking situations.