Statistical properties of four effect-size measures for mediation models

This project examined the performance of classical and Bayesian estimators of four effect size measures for the indirect effect in a single-mediator model and a two-mediator model. Compared to the proportion and ratio mediation effect sizes, standardized mediation effect-size measures were relatively unbiased and efficient in the single-mediator model and the two-mediator model. Percentile and bias-corrected bootstrap interval estimates of ab/s _Y , and ab(s _X )/s _Y in the single-mediator model outperformed interval estimates of the proportion and ratio effect sizes in terms of power, Type I error rate, coverage, imbalance, and interval width. For the two-mediator model, standardized effect-size measures were superior to the proportion and ratio effect-size measures. Furthermore, it was found that Bayesian point and interval summaries of posterior distributions of standardized effect-size measures reduced excessive relative bias for certain parameter combinations. The standardized effect-size measures are the best effect-size measures for quantifying mediated effects.     

Work Engagement of Dual-Working Couples: Dissimilarity and Its Relation to Both Partners’ Well-Being

Work engagement is a positive, fulfilling, work-related state of mind that is characterized by vigor, dedication, and absorption. Work engaged individuals not only function better at work, but also transfer these benefits to home - research has shown that work engagement crosses over between marital partners. In previous studies on crossover, this phenomenon was evidenced only by significant correlation between self-reports of partners’ work engagement, while measures of dissimilarity between partners were completely ignored. However, work engagement dissimilarity - with one partner being highly enthusiastic and immersed in his/her work and the other one lowly - could be related to some aspects of both partners’ well-being and might improve its prediction. Hence, the goal of this study was to examine work engagement dissimilarity within dual-earning couples. In addition to self-report measures, we collected partners’ ratings of work engagement and its subdimensions as well. The data collected on 178 dual-working Croatian couples showed significant correlation of overall work engagement, vigor, dedication and absorption between various pairs of self- and other-ratings measures (partners’ self-ratings; self-ratings and partner’s ratings; and partner’s self-ratings and his/her ratings of work engagement of the partner). Moreover, difference in self-ratings and ratings of partner’s work engagement showed negative correlation with life satisfaction of both partners, suggesting that work engagement dissimilarity has a potential to be related to some aspects of partners’ well-being.     

Clients’ Perception of Outcome of Team-Based Prenatal and Reproductive Genetic Counseling in Serbian Service Using the Perceived Personal Control (PPC) Questionnaire

This is the first study in Serbia and the region of South-East Europe dedicated to clients’ perception of outcome and efficiency of prenatal and reproductive genetic counseling. The primary aim of this study was to assess overall value and success of genetic counseling in prenatal and reproductive care with regard to perceived personal control of clients, reflecting also in a part patient comprehension, knowledge retention, and empowerment in decision-making. The standardized Perceived Personal Control questionnaire (PPC) was used for the assessment of 239 female participants. First, we performed a complete validation of the psychometric characteristics of the Serbian-language version of the PPC questionnaire. The validation of the questionnaire permits other researchers from Serbian-speaking regions of South-East Europe to use this standard instrument to assess the effectiveness of prenatal genetic counseling in their communities and analyze advantages and disadvantages of their counseling models. We also measured social and demographic characteristics of participants. Further, we analyzed effects of our team-based prenatal and reproductive genetic counseling model through (a) calculation of PPC scores at three different stages (before initial, after initial, and before second counseling session), and (b) by assessing participants’ responses by indication for referral (advanced maternal age, abnormal biochemical screening, family history of hereditary disorders, maternal exposure to drugs, exposure to radiation, exposure to infective agents, infertility or recurrent abortions, and miscellaneous). The results indicate that participants’ knowledge after initial counseling increased significantly and after that remained stable and sustainable. A satisfactory level of confidence among participants had been achieved, in that many felt an increased sense of control over their situation and emotional response to it. Indirectly, these results indicate the success of a team-based prenatal genetic counseling model, which has not been assessed in the literature to date.     

Neurophysiologic markers of primary motor cortex for laryngeal muscles and premotor cortex in caudal opercular part of inferior frontal gyrus investigated in motor speech disorder: a navigated transcranial magnetic stimulation (TMS) study

Transcranial magnetic stimulation studies have so far reported the results of mapping the primary motor cortex (M1) for hand and tongue muscles in stuttering disorder. This study was designed to evaluate the feasibility of repetitive navigated transcranial magnetic stimulation (rTMS) for locating the M1 for laryngeal muscle and premotor cortical area in the caudal opercular part of inferior frontal gyrus, corresponding to Broca’s area in stuttering subjects by applying new methodology for mapping these motor speech areas. Sixteen stuttering and eleven control subjects underwent rTMS motor speech mapping using modified patterned rTMS. The subjects performed visual object naming task during rTMS applied to the (a) left M1 for laryngeal muscles for recording corticobulbar motor-evoked potentials (CoMEP) from cricothyroid muscle and (b) left premotor cortical area in the caudal opercular part of inferior frontal gyrus while recording long latency responses (LLR) from cricothyroid muscle. The latency of CoMEP in control subjects was 11.75 ± 2.07 ms and CoMEP amplitude was 294.47 ± 208.87 µV, and in stuttering subjects CoMEP latency was 12.13 ± 0.75 ms and 504.64 ± 487.93 µV CoMEP amplitude. The latency of LLR in control subjects was 52.8 ± 8.6 ms and 54.95 ± 4.86 in stuttering subjects. No significant differences were found in CoMEP latency, CoMEP amplitude, and LLR latency between stuttering and control-fluent speakers. These results indicate there are probably no differences in stuttering compared to controls in functional anatomy of the pathway used for transmission of information from premotor cortex to the M1 cortices for laryngeal muscle representation and from there via corticobulbar tract to laryngeal muscles.     

Posttraumatic symptomatology in children exposed to war

This study examines affective and behavioral symptomatology in two groups of school-age children who were traumatized to different degrees during the war in Croatia (N = 1034). Six self-reported questionnaires were used to assess the following: number and type of war experiences, PTSD symptoms, anxiety, depression, psychosomatic symptoms, and psychosocial adaptation. Canonical discriminant analysis yielded a significant discriminant function that indicates moderate differentiation between the two groups of children according to the assessed symptoms. The results of a 2 x 2 x 2 ANOVAs (gender x age x level of traumatization) indicate that the children's reactions to war traumata varied in respect to all factors, as well as their interaction. The results indicate that gender differences are more prominent in older children. Older girls report more posttraumatic stress reactions, anxiety and depression, but at the same time seem better adapted than boys. Younger children, particularly those who survived more war even report more PTSD symptoms than older children.