The Effect of Sampling-Time Variation on Latent Growth Curve Models

Longitudinal data are often collected in waves in which a participant’s data can be collected at different times within each wave, resulting in sampling-time variation that is unaccounted for when waves are treated as single time points. Little research has been reported on the effects of this temporal imprecision on longitudinal growth-curve modeling. This article describes the results of a simulation study into the effect of sampling-time variation on parameter estimation, model fit, and model comparison with an empirical validation of the model fit and comparison results.     

Why are Older Faculty Members More Accepting of Students with Attention‐deficit Hyperactivity Disorder? A Life‐course Interpretation

The presence of university students in the United States with disabilities is not a new phenomenon. However, little is known about the attitudes of university faculty concerning less visible disabilities such as attention‐deficit hyperactivity disorder (ADHD). Using a sample of faculty at a university in the United States (n = 136), the impact of age on faculty’s acceptance of ADHD was examined. Results indicated a higher percentage of older faculty members, compared with middle‐aged and younger faculty, selected ADHD as a condition worthy of special instructional accommodations. Irrespective of age of the respondents, ADHD had the lowest acceptance as a condition deserving special accommodations. Finally, fewer middle‐aged and older faculty attributed difficulties experienced by a student with ADHD symptoms to “bad” character, a lack of discipline or a lack of motivation. These findings suggest more emphasis should be placed on disability‐related education and training for faculty members during early stages of their careers.     

Another failure to replicate Lynn's estimate of the average IQ of sub-Saharan Africans

In his comment on our literature review of data on the performance of sub-Saharan Africans on Raven's Progressive Matrices, Lynn (this issue) criticized our selection of samples of primary and secondary school students. On the basis of the samples he deemed representative, Lynn concluded that the average IQ of sub-Saharan Africans stands at 67 when compared to UK norms after a correction of the Flynn Effect. We criticize his methods for being unsystematic. Here we select only those samples that were based on stratified or clustered random sampling and were deemed representative by the original authors. We again fail to replicate Lynn's low estimate of the average IQ of Africans. We argue that these scores are hard to interpret in terms of latent cognitive variables such as g because of the psychometric incomparability we established and because the Flynn Effect has yet to take hold in sub-Saharan Africa.     

In practice: The business of doing good: A creative collaboration

Matt Matsuda and David Williams report on a successful collaboration between academic and student services that resulted in a Rutgers University Byrne Seminar on social entrepreneurship.     

Phonological processing and emergent literacy in Spanish-speaking preschool children

Phonological awareness (PA), phonological memory (PM), and phonological access to lexical storage (also known as RAN), play important roles in acquiring literacy. We examined the convergent, discriminant, and predictive validity of these phonological processing abilities (PPAs) in 147 3-, 4-, and 5-year-old children whose native language was Spanish. Confirmatory factor analysis (CFA) supported the validity of each PPA as separate from general cognitive ability and separate from each other. Moreover, structural equation modeling found RAN uniquely associated with knowledge of Spanish letter names and Spanish letter sounds. PA was found the best predictor of children’s ability to distinguish alphabetic text from nonalphabetic text. Finally, general cognitive ability was only indirectly associated with emergent literacy skills via PPAs. These results highlight the importance of PPAs in the early literacy development of native Spanish speaking preschool children.     

Characterising the impact performance of field hockey sticks

Published research on field hockey equipment is scarce. The aim of this research was to investigate methods for characterising the impact performance of field hockey sticks. Three sticks were used with fundamental frequencies in the range 74?C154?Hz. Striking an initially still ball with a stick was identified as the preferred method for characterising performance. Impacts were simulated at mean velocities of 19?m/s at toe and 16?m/s at the shaft. The mean apparent coefficient of restitution and standard deviation were ?0.32?±?0.05 at the toe and ?0.18?±?0.02 at the shaft. The foundation work presented here provides the foundations for developing a methodology for characterising the impact performance of field hockey sticks.     

Movement variability in the golf swing

Traditionally, golf biomechanics has focused upon achieving consistency in swing kinematics and kinetics, whilst variability was considered to be noise and dysfunctional. There has been a growing argument that variability is an intrinsic aspect of skilled motor performance and plays a functional role. Two types of variability are described: 'strategic shot selection' and 'movement variability'. In 'strategic shot selection', the outcome remains consistent, but the swing kinematics/kinetics (resulting in the desired ball flight) are free to vary; 'movement variability' is the changes in swing kinematics and kinetics from trial to trial when the golfer attempts to hit the same shot. These changes will emerge due to constraints of the golfer's body, the environment, and the task. Biomechanical research has focused upon aspects of technique such as elite versus non-elite kinematics, kinetics, kinematic sequencing, peak angular velocities of body segments, wrist function, ground reaction forces, and electromyography, mainly in the search for greater distance and clubhead velocity. To date very little is known about the impact of variability on this complex motor skill, and it has yet to be fully researched to determine where the trade-off between functional and detrimental variability lies when in pursuit of enhanced performance outcomes.     

Relations between physiological and cognitive regulatory systems: infant sleep regulation and subsequent executive functioning

The aim of this report was to investigate the prospective links between infant sleep regulation and subsequent executive functioning (EF). The authors assessed sleep regulation through a parent sleep diary when children were 12 and 18 months old (N = 60). Child EF was assessed at 18 and 26 months of age. Higher proportions of total sleep occurring at night time, at both 12 and 18 months, were related to better performance on executive tasks, especially those involving a strong impulse control component. Most relations held above family socioeconomic status, prior mental development and concurrent verbal ability. These findings add to previous results with school-age children in suggesting that sleep favors the development of higher order cognitive functions requiring prefrontal cortex involvement.