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281.
Chayna J. Davis Valerie S. Knopik Richard K. Olson Sally J. Wadsworth John C. DeFries 《Annals of dyslexia》2001,51(1):231-247
The present study assesses the genetic and environmental etiologies of reading, rapid naming (RN), and their covariation by
fitting multivariate structural equation models to data from 587 twin pairs in which at least one member of the pair exhibited
reading difficulties (low-range) and from 360 control (normal-range) twin pairs who were tested in the Colorado Learning Disabilities
Research Center. Results from a bivariate phenotypic analysis with two hypothesized latent factors, READ and RN, indicated
that the correlation between reading and rapid naming performance for the low-range sample was significantly higher than that
of the normal-range sample. When this model was partitioned to include estimates of genetic, shared environmental, and nonshared
environmental influences, resulting heritability estimates did not differ significantly for the low-range and normal-range
samples for either READ or RN. However, similar to the phenotypic correlation, the genetic correlation between the READ and
RN latent factors could not be equated for the two groups. Thus, the etiology of the relationship between reading performance
and rapid naming may differ for children with reading difficulties and normally-achieving readers. Moreover, these results
support previous findings that the best predictors of reading skills may differ for samples of children with normal reading
levels and those with reading difficulties. 相似文献
282.
Models to assess mediation in the pretest–posttest control group design are understudied in the behavioral sciences even though it is the design of choice for evaluating experimental manipulations. The article provides analytical comparisons of the four most commonly used models to estimate the mediated effect in this design: analysis of covariance (ANCOVA), difference score, residualized change score, and cross-sectional model. Each of these models is fitted using a latent change score specification and a simulation study assessed bias, Type I error, power, and confidence interval coverage of the four models. All but the ANCOVA model make stringent assumptions about the stability and cross-lagged relations of the mediator and outcome that might not be plausible in real-world applications. When these assumptions do not hold, Type I error and statistical power results suggest that only the ANCOVA model has good performance. The four models are applied to an empirical example. 相似文献
283.
This paper reports on efforts aimed toward the development of more effective procedures for identifying mothers who are at elevated risk for problems in parenting. We present data from two independent samples of known maladaptors and corresponding comparison mothers and report on our attempts to cross-validate a promising screening instrument composed of items that index social support and parenting attitudes. The resultant 20-item scale correctly identified over 90% of maladaptive and comparison mothers. When this scale was cross-validated on a second independent sample of maladaptors and comparison mothers, it was again almost 90% accurate. Issues concerning the field application of this promising instrument are discussed and its possible limitations are considered. 相似文献
284.
Randomised controlled trials (RCTs) are often seen as the 'gold standard' of evaluative research. However, whilst randomisation will ensure comparable groups, trials are still vulnerable to a range of biases that can undermine their internal validity. In this paper we describe a number of common threats to the internal validity of RCTs and methods of countering them. We highlight a number of examples from randomised trials in education and health care where problems of execution and analysis of the RCT has undermined their internal validity. However, awareness of these potential biases can lead to careful planning to avoid or reduce their occurrence. If good quality randomised trials are to inform policy and practice in education then rigorous trials need to be designed that are the least susceptible to threats to their validity. 相似文献
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286.
Cynthia J. Osborn Erin M. West William Z. Nance 《Counselor Education & Supervision》2017,56(2):112-129
Eight professional counselors who routinely role‐play as clients in 1 counselor education program participated in a focus group investigating their portrayal experiences. Data were analyzed using interpretative phenomenological analysis, which resulted in 3 superordinate themes: missions, influential factors, and repercussions. Findings reinforce instruction of idiographic and person‐centered care in counselor education. 相似文献
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