Prenatal Reflective Functioning and Accumulated Risk as Predictors of Maternal Interactive Behavior During Free Play,the Still‐Face Paradigm,and Two Teaching Tasks

This study examined whether prenatal reflective functioning (RF) was related to mothers’ interactive style across contexts with their 6‐month‐old infants (M age = 6.02 months, SD = 0.41, 54% boys), and to what extent quality of prenatal RF could account for the influence of accumulated risk on maternal interactive behavior. Accumulated risk was defined as the sum‐score of a selection of risk factors that have been associated with suboptimal infant development. Mother–infant dyads (N = 133) were observed during free play, two teaching tasks, and the Still‐Face Paradigm (SFP). Better prenatal RF was associated with more positive maternal behavior in all settings and less negative behavior during teaching and SFP reengagement. Accumulated risk and prenatal RF predicted shared variance in maternal interactive behavior (with unique predictive effects observed only for RF on sensitivity during teaching and SFP play, and for accumulated risk on sensitivity and positive engagement during SFP play, and internalizing‐helplessness during SFP reengagement). Accumulated risk had an indirect effect on maternal sensitivity during teaching and SFP play through prenatal RF. These findings suggest not only that RF may be targeted prenatally to improve mother–infant interactions, but also that enhancing RF skills may ameliorate some of the negative consequences from more stable perinatal risk factors that influence parent–child interactions.     

Handling of missing data in long‐term clinical trials: a case study

Missing data in clinical trials is a well‐known problem, and the classical statistical methods used can be overly simple. This case study shows how well‐established missing data theory can be applied to efficacy data collected in a long‐term open‐label trial with a discontinuation rate of almost 50%. Satisfaction with treatment in chronically constipated patients was the efficacy measure assessed at baseline and every 3 months postbaseline. The improvement in treatment satisfaction from baseline was originally analyzed with a paired t‐test ignoring missing data and discarding the correlation structure of the longitudinal data. As the original analysis started from missing completely at random assumptions regarding the missing data process, the satisfaction data were re‐examined, and several missing at random (MAR) and missing not at random (MNAR) techniques resulted in adjusted estimate for the improvement in satisfaction over 12 months. Throughout the different sensitivity analyses, the effect sizes remained significant and clinically relevant. Thus, even for an open‐label trial design, sensitivity analysis, with different assumptions for the nature of dropouts (MAR or MNAR) and with different classes of models (selection, pattern‐mixture, or multiple imputation models), has been found useful and provides evidence towards the robustness of the original analyses; additional sensitivity analyses could be undertaken to further qualify robustness. Copyright © 2012 John Wiley & Sons, Ltd.     

Prenatal risk and physical aggression during the first years of life: The gender‐specific role of inhibitory control

Prenatal risk and a lack of inhibitory control have consistently been related to the development of physical aggression in older children. This study examined whether inhibitory control mediated the relation between prenatal risk and aggression in infants and toddlers. The role of gender in this mediation model was also examined. The sample consisted of 161 mother–child dyads (83 boys). A prenatal cumulative risk score was created from a number of well‐established risk factors including maternal psychopathology, substance use, and social and socioeconomic disadvantages. At 12 months, children performed an inhibitory control task. Physical aggression was assessed through maternal reports at 12 and 20 months of age. Results showed that higher prenatal risk was associated with more physical aggression. Inhibitory control mediated this association at both 12 and 20 months: higher prenatal risk was related to lower inhibitory control, which in turn led to higher aggression. At 20 months, gender moderated the mediation effect: the mediating role of inhibitory control was only found for girls. These results suggest that even before 2 years of age, inhibitory control is an important construct involved in the relation between prenatal risk and physical aggression.     

Multi-horizon Markowitz portfolio performance appraisals: A general approach

This article extends the analysis of multi-horizon mean-variance portfolio analysis in the Morey and Morey [Mutual fund performance appraisals: a multi-horizon perspective with endogenous benchmarking. Omega 1999;27:241–58] article in several ways. First, instead of either proportionally contracting risk dimensions or proportionally expanding return dimensions, a more general efficiency measure simultaneously attempts to reduce risk and to expand return over all time periods. Second, a duality relation is established between this generalized multi-horizon efficiency measure and an indirect mean-variance utility function, underscoring the natural interpretation of this generalized efficiency measure in terms of investor's preferences. Furthermore, the need to properly apply time discounting in multi-horizon mean-variance portfolio problems is argued for. An empirical illustration based on the original mutual fund data set in Morey and Morey [Mutual fund performance appraisals: a multi-horizon perspective with endogenous benchmarking. Omega 1999;27:241–58] is added to contrast the new and the original approaches.     

Aggression in toddlerhood: The roles of parental beliefs,parenting behavior and precursors of theory of mind

Parental beliefs, parenting behavior, and precursors of theory of mind have been related uniquely to each other and to early aggression, but have not yet been studied simultaneously. The present study combined these risk factors in the prediction of aggression during toddlerhood using a sample of 152 mother–child dyads. At 20 months, mothers' parental beliefs (parental self‐efficacy and perceived parental impact) were examined with the Parental Cognitions and Conduct Toward the Infant Scale. Maternal parenting behavior (sensitivity, intrusiveness, and successful positive engagement) was observed during free play and teaching tasks, and children's precursors of theory of mind were assessed using a visual perspectives task and an imitation task. At 30 months, child aggression was examined using the Child Behavior Checklist. A regression analysis indicated that lower parental self‐efficacy and lower imitation skills predicted more aggressive behavior. When estimating the indirect effects using bootstrapping, a final model was found indicating that lower perceived parental impact was related to less successful positive engagement, which, in turn, was associated with children's poorer imitation abilities which predicted more aggressive behavior. It can be concluded that aggression during toddlerhood is predicted significantly by interrelated parental beliefs, parenting behavior, and children's early social cognitive abilities.     

Technology-based total factor productivity and benchmarking: New proposals and an application

The present study fills a gap between the benchmarking literature and multi-output based efficiency and productivity studies by proposing a benchmarking framework to analyze total factor productivity (TFP). Different specifications of the Hicks–Moorsteen TFP index are tailored for specific benchmarking perspectives: (1) static, (2) fixed base and unit, and (3) dynamic TFP change. These approaches assume fixed units and/or base technologies as benchmarks. In contrast to most technology-based productivity indices, the standard Hicks–Moorsteen index always leads to feasible results. Through these specifications, managers can assess different facets of the firm's strategic choices in comparison with firm-specific relevant benchmarks and thus have a broad background for decision making. An empirical application for the Spanish banking industry between 1998 and 2006 illustrates the managerial implications of the proposed framework.     

A Computational Study of Replicated Clustering with an Application to Market Segmentation*

In most commercial applications of k-means clustering, researchers choose one set of kseed points to start the partitioning process; often, the initial set of seeds is chosen randomly. Using Monte Carlo simulation, we show that significant benefits are associated with replicated starting configurations that incorporate seed selection procedures based on a hierarchical clustering of sample points drawn from the original data matrix. A real-world application of the approach is then presented.