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51.
Factor analysis is regularly used for analyzing survey data. Missing data, data with outliers and consequently nonnormal data are very common for data obtained through questionnaires. Based on covariance matrix estimates for such nonstandard samples, a unified approach for factor analysis is developed. By generalizing the approach of maximum likelihood under constraints, statistical properties of the estimates for factor loadings and error variances are obtained. A rescaled Bartlett-corrected statistic is proposed for evaluating the number of factors. Equivariance and invariance of parameter estimates and their standard errors for canonical, varimax, and normalized varimax rotations are discussed. Numerical results illustrate the sensitivity of classical methods and advantages of the proposed procedures.This project was supported by a University of North Texas Faculty Research Grant, Grant #R49/CCR610528 for Disease Control and Prevention from the National Center for Injury Prevention and Control, and Grant DA01070 from the National Institute on Drug Abuse. The results do not necessarily represent the official view of the funding agencies. The authors are grateful to three reviewers for suggestions that improved the presentation of this paper. 相似文献
52.
We introduce non-associative linear logic, which may be seen as the classical version of the non-associative Lambek calculus. We define its sequent calculus, its theory of proof-nets, for which we give a correctness criterion and a sequentialization theorem, and we show proof search in it is polynomial. 相似文献
53.
In this paper we consider the relations existing between four deductive systems that have been called categorial grammars and have relevant connections with linguistic investigations: the syntactic calculus, bilinear logic, compact bilinear logic and Curry's semantic calculus. 相似文献
54.
Simkins-Bullock J 《Neuropsychology review》2000,10(1):41-74
While the intracarotid amobarbital procedure (IAP) was originally utilized to lateralize speech functions as an aid in the surgical treatment of epilepsy, additional uses for the IAP have emerged including: (1) the use of the IAP to predict post-surgical memory changes, including both global amnesia and smaller, yet significant, material-specific memory deficits; (2) the use of the IAP to provide confirmatory evidence of lateralization of seizure focus; and (3) the use of the IAP to predict post-surgical relief from seizures. While the literature on the IAP is extensive and growing, its utility is marred by the wide variability associated with the procedure itself from epilepsy center to center. This variability renders comparisons among IAP studies problematic and conclusions about IAP efficacy difficult. The variability associated with the amobarbital procedures, as well as the reliability and the validity of the IAP in its nonlanguage uses is reviewed here. A special emphasis is devoted to research conducted in the last decade. Also discussed is the future of the IAP including anticipated research directions. 相似文献
55.
Launis V 《Science and engineering ethics》2000,6(3):299-310
In the bioethical literature, discrimination in insurance on the basis of genetic risk factors detected by genetic testing
has been defended and opposed on various ethical grounds. One important argument in favour of the practice is offered by those
who believe that it is not possible to distinguish between genetic and non-genetic information, at least not for practical
policy purposes such as insurance decision-making. According to the argument from indistinguishability, the use of genetic
test information for insurance purposes should be permitted, because genetic test information is no different from non-genetic
medical information in any relevant respect, therefore it would be inconsistent to prohibit the former whilst permitting the
latter. This paper discusses and defends this argument and suggests a new, more tenable foundation. 相似文献
56.
中小学生认知能力发展水平测验的研究 总被引:4,自引:0,他引:4
以皮亚杰的认知发展理论为基础,采用皮亚杰及其学生研究认知发展时的任务为测验题目,编制成测量中小学生认知能力发展水平的测验.通过对2240名中小学生施测,结果表明本测验不仅具有很好的信度和效度,而且也具有适中的难度.然后以一所中学特长班学生为被试,通过对他们进行测量,并将测验结果与同年级普通班学生的认知成绩进行比较,结果存在很明显的差异.最后对中小学生认知能力发展水平测量问题进行了探讨. 相似文献
57.
Two new tests for a model for the response times on pure speed tests by Rasch (1960) are proposed. The model is based on the
assumption that the test response times are approximately gamma distributed, with known index parameters and unknown rate
parameters. The rate parameters are decomposed in a subject ability parameter and a test difficulty parameter. By treating
the ability as a gamma distributed random variable, maximum marginal likelihood (MML) estimators for the test difficulty parameters
and the parameters of the ability distribution are easily derived. Also the model tests proposed here pertain to the framework
of MML. Two tests or modification indices are proposed. The first one is focused on the assumption of local stochastic independence,
the second one on the assumption of the test characteristic functions. The tests are based on Lagrange multiplier statistics,
and can therefore be computed using the parameter estimates under the null model. Therefore, model violations for all items
and pairs of items can be assessed as a by-product of one single estimation run. Power studies and applications to real data
are included as numerical examples. 相似文献
58.
Quantized Linear Logic,Involutive Quantales and Strong Negation 总被引:1,自引:0,他引:1
A new logic, quantized intuitionistic linear logic (QILL), is introduced, and is closely related to the logic which corresponds to Mulvey and Pelletier's (commutative) involutive quantales. Some cut-free sequent calculi with a new property quantization principle and some complete semantics such as an involutive quantale model and a quantale model are obtained for QILL. The relationship between QILL and Wansing's extended intuitionistic linear logic with strong negation is also observed using such syntactical and semantical frameworks. 相似文献
59.
60.
Riolobos AS Heredia M de la Fuente JA Criado JM Yajeya J Campos J Santacana M 《Neurobiology of learning and memory》2001,75(3):274-292
The long-term effect of transplanting embryonic frontal cortex into a unilateral frontal cortex lesion has been studied in adult rats. Before surgery, activity in an open field, muscular strength of both forelimbs, and performance in a paw-reaching-for-food task were scored in 26 rats. In 21 animals a unilateral cortex lesion was then made in the forelimb motor area of the hemisphere contralateral to the preferred paw in the paw-reaching-for-food task, while the other 5 animals were sham-operated. On retesting, the lesion animals changed the preferred paw. A solid homotopic transplant of embryonic tissue (embryonic day 17) was then placed in the lesion cavity in 11 of the lesion rats. Three months later neither lesion alone nor lesion plus transplantation affected open field behavior and muscular strength, but the lesion permanently affected performance in the paw-reaching-for-food task, as shown by a change of preferred paw and a functional deficit in the paw contralateral to the lesion. Transplantation ameliorated the deficits caused by the lesion, but this was only evident when animals were forced to reach with the paw contralateral to the lesion plus transplant. The behavioral results were independent of the size of the lesion and graft. Connections between graft and host tissue were studied by means of the fluorescent tracer 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI). A dense array of labeled fibers was found in the host cortex adjacent to the transplant. The results suggest that functional recovery depends on grafting but is only evident when the animal is obliged to use the affected limb. 相似文献