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This meta-analysis examined the association between Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms and lead exposure in children and adolescents. Thirty-three studies published between 1972 and 2010 involving 10,232 children and adolescents were included. There was a small to medium association between inattention symptoms and lead exposure(More)
Although psychopathy is frequently regarded as qualitatively distinct from other conditions, relatively little research has examined whether psychopaths represent a distinct class of individuals. Using a sample of 876 prison inmates and court-ordered substance abuse patients who were administered the Psychopathy Checklist-Revised (R. D. Hare, 2003), the(More)
An understanding of the latent structure of attention-deficit/hyperactivity disorder (ADHD) is essential for developing causal models of this disorder. Although some researchers have presumed that ADHD is dimensional and others have assumed that it is taxonic, there has been relatively little research directly examining the latent structure of ADHD. The(More)
On the basis of taxometric analyses of data sets that they created to pose interpretive challenges, S. R. H. Beach, N. Amir, and J. J. Bau (2005) cautioned that using comparison data simulated by J. Ruscio's programs can lead to inaccurate conclusions. Careful examination of S. R. H. Beach et al.'s methods and results plus reanalysis of their data fails to(More)
Psychopathy or psychopathic personality disorder represents a constellation of traits characterized by superficial charm, egocentricity, irresponsibility, fearlessness, persistent violation of social norms, and a lack of empathy, guilt, and remorse. Factor analyses of the Psychopathic Personality Inventory (PPI)typically yield two factors: Fearless(More)
A number of recent studies have used Meehl's (1995) taxometric method to determine empirically whether one should model assessment-related constructs as categories or dimensions. The taxometric method includes multiple data-analytic procedures designed to check the consistency of results. The goal is to differentiate between strong evidence of categorical(More)
This review examined (a) whether hypochondriacal/health-anxious individuals hold distinct assumptions about health and illness, (b) if triggering these assumptions leads to increased hypochondriacal concerns, and (c) whether these individuals perceive their bodily sensations differently from others (i.e., experience greater somatosensory amplification).(More)
Studies of the therapeutic alliance typically use a one-with-many (OWM) design in which each therapist (the one) treats multiple clients (the many). This study used Kenny, Kashy, and Cook's (2006) OWM method to examine the composition of the therapeutic alliance and to analyze the association between alliance and outcome in a sample of 398 adolescents(More)
Although a common assumption throughout much of the professional and popular literature is that psychopaths are qualitatively different from others, very few studies have examined the latent structure of psychopathy. Whether psychopathy is a discrete category or a continuous dimension may have implications for research on the assessment, etiology, and(More)