Power and Sample Size Calculations for Contrast Analysis in ANCOVA

Analysis of covariance (ANCOVA) is commonly used in behavioral and educational research to reduce the error variance and improve the power of analysis of variance by adjusting the covariate effects. For planning and evaluating randomized ANCOVA designs, a simple sample-size formula has been proposed to account for the variance deflation factor in the comparison of two treatment groups. The objective of this article is to highlight an overlooked and potential problem of the exiting approximation and to provide an alternative and exact solution of power and sample size assessments for testing treatment contrasts. Numerical investigations are conducted to reveal the relative performance of the two procedures as a reliable technique to accommodate the covariate features that make ANCOVA design particularly distinctive. The described approach has important advantages over the current method in general applicability, methodological justification, and overall accuracy. To enhance the practical usefulness, computer algorithms are presented to implement the recommended power calculations and sample-size determinations.     

Les gestes en autoconfrontation croisée : enjeux et pratiques

This article aims to show how the relationship between gestures and speech can help understand mechanisms of activity's development. In situation of self-confrontation work analysis between two workers, we study more precisely the repetition of a sweep gesture made by one of the two professionals and repeated by the other one. We argue that this type of repetition highlights development of activities mechanisms. From two extracts from a cross self-confrontation, we analyze the coordination between speech and gestures. We finally show that mismatches between gestures and speech make possible to understand development of activity of these professionals in this particular context. As a conclusion, the hypothesis that this development may be one of the origins of the transformation of action in ordinary work situations is advanced.     

The role of simultaneous and successive processing in EFL reading

This study examines the relationship between simultaneous and successive processing (the Planning, Attention, Simultaneous and Successive processing [PASS] theory processes) and reading skills in English as a foreign language (EFL). A group of 81 children were administered two batteries of tests. One was used to measure EFL reading skills, while the other one assessed simultaneous and successive processing. We hypothesised (a) cognitive processes to predict reading ability, as well as (b) the presence of a significant relationship between (c) simultaneous processing and reading comprehension and (d) successive processing and letter and word decoding. The findings confirmed that the anticipated relationships between these domains exist and are of moderate effect size. The research has helped to contribute to the understanding of how simultaneous and successive processing can affect EFL reading skills both on the level of basic word and letter decoding and reading comprehension.     

Power Analysis for the Likelihood-Ratio Test in Latent Markov Models: Shortcutting the Bootstrap p-Value-Based Method

The latent Markov (LM) model is a popular method for identifying distinct unobserved states and transitions between these states over time in longitudinally observed responses. The bootstrap likelihood-ratio (BLR) test yields the most rigorous test for determining the number of latent states, yet little is known about power analysis for this test. Power could be computed as the proportion of the bootstrap p values (PBP) for which the null hypothesis is rejected. This requires performing the full bootstrap procedure for a large number of samples generated from the model under the alternative hypothesis, which is computationally infeasible in most situations. This article presents a computationally feasible shortcut method for power computation for the BLR test. The shortcut method involves the following simple steps: (1) obtaining the parameters of the model under the null hypothesis, (2) constructing the empirical distributions of the likelihood ratio under the null and alternative hypotheses via Monte Carlo simulations, and (3) using these empirical distributions to compute the power. We evaluate the performance of the shortcut method by comparing it to the PBP method and, moreover, show how the shortcut method can be used for sample-size determination.     

"You" and "I," "us " and them: a systemic-discursive approach to the study of ethnic stereotypes in the context of British-Greek heterosexual couple relationships

Systemic family therapy accounts of ethnic stereotypes in the context of ethnically mixed couple relationships have tended to focus on the interpersonal-psychological realm of the couple relationship. Discourse analytic research, on the other hand, has highlighted the role of such stereotypes in the construction of national identity and has stressed the importance of a historical and ideological approach. In this article, we will present our attempt to develop a systemic-discursive approach to the study of stereotypes in the particular context of British-Greek heterosexual couple relationships by building on both fields.     

Counsellors’ and psychologists’ experience of working with male survivors of sexual trauma: a pilot study

A qualitative study was undertaken to enhance awareness of the therapeutic needs of the male survivor of sexual trauma through exploration of counsellors’ and psychologists’ experience of working with this client group. The participants were 32 counsellors and psychologists who work for an NHS Trust department. Interpretative Phenomenological Analysis was used to analyse the data which was gathered by means of a postal questionnaire. Six categories emerged from the analysis that highlighted prevalent experience. These were: (a) that the therapist's gender was important, (b) professional concerns, (c) the importance of the relationship, (d) transference/counter transference, (e) that male and female abusive experiences are the same and (f) attention to client's presenting problems. The main conclusions derived from these results and implications for practice are considered.     

Building an Expanded Therapeutic Alliance: A Task Analysis with Families Trapped in Parental-Adolescent Conflict

Parental-adolescent conflict is part of the normal developmental cycle of families, but when it occurs in a dysfunctional way, it is associated with the appearance of various harmful conditions for the family system and for the adolescent in particular. Family therapy is one of the main options for psychotherapeutic intervention in these cases and has ample evidence of its effectiveness. The success of this intervention is conditioned to the construction of an adequate therapeutic alliance with the family, but the process of this task has not been clarified yet. The present study is a task analysis, the purpose of which was to create a heuristic model of how an expanded alliance may be built in these kinds of cases. The model was revised and improved from the intensive analysis of six cases. The resulting model can be a useful guide for family therapists in that it describes the specific client and therapist behaviors involved in balancing the alliance, as well as the potential obstacles and suggested ways to resolve them.     

A Task Analysis of Client Re-engagement: Therapeutic De-escalation of High-Conflict Coparents

Parents who are engaged in protracted conflict following a divorce are often referred to coparenting therapy. Episodes of intense conflict are common during these therapy sessions and often result in coparents disengaging from the therapist while they engage in escalating conflict with each other, potentially disrupting their progress in therapy. The purpose of this study was to identify how therapists successfully re-engage clients in the session. To understand this process, 24 disengagement events (12 successful and 12 unsuccessful) from 13 cases were analyzed using a task analytic approach. The sample included coparent dyads referred by the judicial system to a high-conflict coparenting therapy program. Task analysis was used to create a model of how re-engagement unfolds in treatment. The empirical model that resulted has five phases: (1) disengagement from the therapeutic process, (2) disruption of the conflict, (3) de-escalating the most escalated coparent, (4) de-escalating the other coparent, and (5) therapist buffered re-engagement. Successful episodes of re-engagement tended to have therapists who remained active throughout the conflict episode, used structuring interventions aimed at disrupting and then regulating the most escalated partner, blocked attempts to re-engage in conflict, and then repeated this process with the less escalated partner. Additional interventions that promote therapeutic re-engagement are described for each phase, and implications for clinicians and researchers are discussed.