Two simple approximations to the distributions of quadratic forms

Many test statistics are asymptotically equivalent to quadratic forms of normal variables, which are further equivalent to with z_i being independent and following N(0,1). Two approximations to the distribution of T have been implemented in popular software and are widely used in evaluating various models. It is important to know how accurate these approximations are when compared to each other and to the exact distribution of T. The paper systematically studies the quality of the two approximations and examines the effect of the λ_i and the degrees of freedom d by analysis and Monte Carlo. The results imply that the adjusted distribution for T can be as good as knowing its exact distribution. When the coefficient of variation of the λ_i is small, the rescaled statistic is also adequate for practical model inference. But comparing T_R against will inflate type I errors when substantial differences exist among the λ_i, especially, when d is also large.     

cluster types of attitudes toward multiple role planning of single,korean, female undergraduates

The current study explored the attitudes that single, Korean, female college students have toward multiple role planning. Cluster groups among the participants were identified by their scores on the Korean language version (Yang, 1997) of the Attitudes Toward Multiple Role Planning (ATMRP; Weitzman, 1992) measure, and significant differences in career‐ and marriage‐related variables were also examined. Five clusters were derived using cluster analysis based on participants' scores on the ATMRP. Significant differences among clusters were found on career‐ and marriage‐related variables. This study contributes to the understanding of various patterns in attitudes toward multiple roles and suggests effective interventions for each group in the career decision‐making process.     

Approach/Positive Anticipation,Frustration/Anger,and Overt Aggression in Childhood

ABSTRACT We examined mothers' ratings of children's affective and behavioral aspects of approach tendencies and links with overt aggressive behavior problems while considering the genetic etiology of these processes. Approach/positive anticipation (AP), frustration/anger (FA), and overt aggression in 4–9‐year‐olds were assessed using mothers' reports in a diverse national sample (n=992) and a sample of same‐sex twins (n=195 pairs). AP and FA were positively correlated with each other and with overt aggression (r from .2 to .5), and these associations were very similar for boys and girls. AP and FA provided overlapping as well as independent statistical prediction of aggression. AP statistical prediction of aggression was substantially mediated by FA, an effect that was accounted for by underlying genetic and nonshared environmental influences.     

Visual‐motor and executive functions in children born preterm: The Bender Visual Motor Gestalt Test revisited

Böhm, B., Lundequist, A. & Smedler, A.‐C. (2010). Visual‐motor and executive functions in children born preterm: The Bender Visual Motor Gestalt Test revisited. Scandinavian Journal of Psychology, 51, 376–384. Visual‐motor development and executive functions were investigated with the Bender Test at age 5½ years in 175 children born preterm and 125 full‐term controls, within the longitudinal Stockholm Neonatal Project. Assessment also included WPPSI‐R and NEPSY neuropsychological battery for ages 4–7 ( Korkman, 1990 ). Bender protocols were scored according to Brannigan & Decker (2003) , Koppitz (1963) and a complementary neuropsychological scoring system (ABC), aimed at executive functions and developed for this study. Bender results by all three scoring systems were strongly related to overall cognitive level (Performance IQ), in both groups. The preterm group displayed inferior visual‐motor skills compared to controls also when controlling for IQ. The largest group differences were found on the ABC scoring, which shared unique variance with NEPSY tests of executive function. Multiple regression analyses showed that hyperactive behavior and inattention increased the risk for visual‐motor deficits in children born preterm, whereas no added risk was seen among hyperactive term children. Gender differences favoring girls were strongest within the preterm group, presumably reflecting the specific vulnerability of preterm boys. The results indicate that preterm children develop a different neurobehavioral organization from children born at term, and that the Bender test with a neuropsychological scoring is a useful tool in developmental screening around school start.     

IN DEFENCE OF FICTIONAL INCOMPETENCE

The claim that photographs are fictionally incompetent (i.e. that they can only depict those particulars they are appropriately causally related to) is argued by Noël Carroll, Gregory Currie, and Nigel Warburton to be falsified by cinematic works of fiction. In response I firstly argue that it does not follow from cinema's having a capacity for the representation of ficta that photography has a capacity for the representation of ficta. Secondly, and inspired by the work of Roger Scruton, I develop an account of how it is that cinema represents ficta on which this is fundamentally a matter of dramatic/theatrical representation. I argue that in cinematic fiction photography delivers a pre‐existent representation of ficta rather than creating or generating fictional content. With this being so, the claim that photography is fictionally incompetent is compatible with cinematic fiction. 1     

Are True Scores and Construct Scores the Same? A critical examination of their substitutability and the implications for research results

Relations between constructs are estimated based on correlations between measures of constructs corrected for measurement error. This process assumes that the true scores on the measure are linearly related to construct scores, an assumption that may not hold. We examined the extent to which differences in distribution shape reduce the correlation between true scores on a measure and scores on the underlying construct they are intended to measure. We found, via a series of Monte Carlo simulations, that when the actual construct distribution is normal, nonnormal distributions of true scores caused this correlation to drop by an average of only .02 across 15 conditions. When both construct and true score distributions assumed different combinations of nonnormal distributions, the average correlation was reduced by .05 across 375 conditions. We conclude that theory‐based scales intended to measure constructs usually correlate highly with the constructs they are constructed to measure. We show that, as a result, in most cases true score correlations only modestly underestimate correlations between different constructs. However, in cases in which the two constructs are redundant, this underestimation can lead to the false conclusion that the constructs are ‘correlated but distinct constructs,’ resulting in construct proliferation.