模拟互变问题解决认知策略的实验研究

本实验通过对模拟互变问题解决认知策略的定性和定量分析,研究认知策略的类型及其信息加工程序。结果表明,存在尝试性策略、分析性策略和直觉性策略三类策略。最佳策略属于分析性策略。     

Genetic Counseling: Clinical Geneticists' Views

Evaluation of genetic counseling requires a clear consensus about its objectives, which is not evident in published definitions and guidelines. This study aims to investigate clinical geneticists' beliefs and thoughts about their practice. Structured interviews with eight clinical geneticists addressed the aims, skills, and expectations of genetic counseling. Analysis of transcribed interviews revealed four key themes, with contradictory aspects: 1. Providing information that is objective, full, and accurate versus information that is contingent on circumstances and tailored to individual needs. 2. Eliciting emotion and dealing with it directly versus dampening down and containing emotion. 3. Communicating nondirectively versus directively. 4. Expecting to perform a range of sophisticated tasks while having minimal training in the necessary skills to achieve these. These results have implications for the nature of the professional role, the development of training required for it, and the evaluation of genetic counseling.     

Are General Practitioners Willing and Able to Provide Genetic Services for Common Diseases?

Primary care in the United Kingdom has been advocated as an optimal location for the provision of genetic services for common diseases. Little, however, is known about general practitioners' own views toward this suggestion or the possible demand for such services from patients. To assess general practitioners' attitudes to providing genetic services for common diseases, and to estimate the demand from patients for these services, we used a single-page postal questionnaire survey of all 359 general practitioners registered with the Oxfordshire Health Authority; 339 (94%) responded. These physicians reported that a mean 4.1 patients (95% CI, 3.3–4.9) out of every 1,000 consulting them were concerned about their own risk of a common disease associated with a diagnosis in a family member. Half of the general practitioners (95% CI, 45–56%) counseled about genetics in the last year. A majority of general practitioners accept the need to provide genetic services, but far fewer are competent to do so. Although 60% (95% CI, 55–65%) believed they should be involved with genetic screening for common diseases, only 29% (95% CI, 24–34%) felt sufficiently prepared to take family histories and draw pedigrees, and only 15% (95% CI, 11–19%) felt sufficiently prepared to counsel patients about their genetic test results. Given the necessary training and information, 63% (95% CI, 58–68%) and 64% (95% CI, 59–69%) were willing to provide these services. Even with training and information, not all would be willing to provide these services, and lack of time may be a major deterrent. Practice-enabling strategies, such as computerized aids in genetics, may be useful.     

A note to Bollen's alternative fit measure

The problem of dependence of the nonnormed fit index on sample size in covariance structure analysis is discussed. Contrary to Bollen (1986) we show that the mean of the nonnormed fit index is independent of sample size for true and almost true models whereas Bollen's alternative index does depend on sample size.     

Improper solutions in the analysis of covariance structures: Their interpretability and a comparison of alternate respecifications

A Monte Carlo approach was employed to investigate the interpretability of improper solutions caused by sampling error in maximum likelihood confirmatory factor analysis. Four models were studied with two sample sizes. Of the overall goodness-of-fit indices provided by the LISREL VI program significant differences between improper and proper solutions were found only for the root mean square residual. As expected, indicators of the factor on which the negative uniqueness estimate occurred had biased loadings, and the correlations of its factor with other factors were also biased. In contrast, the loadings of indicators on other factors and those factor intercorrelations did not have any bias of practical significance. For initial solutions with one negative uniqueness estimate, three respecifications were studied: Fix the uniqueness at .00, fix it at .20, or constrain the domain of the solution to be proper. For alternate, respecified solutions that were converged and proper, the constrained solutions and uniqueness fixed at .00 solutions were equivalent. The mean goodness-of-fit and pattern coefficient values for the original improper solutions were not meaningfully different from those obtained under the constrained and uniqueness fixed at .00 respecifications.This investigation was supported in part by a grant from the Baylor University Research Committee (#018-F83-URC). The authors gratefully acknowledge the comments and suggestions of Claes Fornell and Roger E. Kirk, and the assistance of Timothy J. Vance with the analysis.     

Estimation of covariance structure models with parameters subject to functional restraints

This paper demonstrates the feasibility of using the penalty function method to estimate parameters that are subject to a set of functional constraints in covariance structure analysis. Both types of inequality and equality constraints are studied. The approaches of maximum likelihood and generalized least squares estimation are considered. A modified Scoring algorithm and a modified Gauss-Newton algorithm are implemented to produce the appropriate constrained estimates. The methodology is illustrated by its applications to Heywood cases in confirmatory factor analysis, quasi-Weiner simplex model, and multitrait-multimethod matrix analysis.The author is indebted to several anonymous reviewers for creative suggestions for improvement of this paper. Computer funding is provided by the Computer Services Centre, The Chinese University of Hong Kong.     

II. Genotype-environment interaction in the schizophrenia spectrum: qualitative observations

Previous reports from the Finnish Adoptive Family Study of Schizophrenia have documented significant interplay between genetics (G) and family rearing (E), leading to adoptee outcomes of schizophrenia spectrum disorders. Quantitative evidence for this interplay is significantly enhanced when both high genetic liability and severe environmental dysfunction are present. However, when either genetic liability is low or the rearing environment is healthy, the adoptees appear to be resiliently protected against a pathologic outcome. Nevertheless, exceptions to this pattern do occur. Six qualitative vignettes, together with quantitative measures and categorical diagnoses from the same families, illustrate how multiple methods partially confirm one another and also suggest where further exploration of gene-environment interaction is needed.     

On muthén’s maximum likelihood for two-level covariance structure models

Data in social and behavioral sciences are often hierarchically organized. Special statistical procedures that take into account the dependence of such observations have been developed. Among procedures for 2-level covariance structure analysis, Muthén’s maximum likelihood (MUML) has the advantage of easier computation and faster convergence. When data are balanced, MUML is equivalent to the maximum likelihood procedure. Simulation results in the literature endorse the MUML procedure also for unbalanced data. This paper studies the analytical properties of the MUML procedure in general. The results indicate that the MUML procedure leads to correct model inference asymptotically when level-2 sample size goes to infinity and the coefficient of variation of the level-1 sample sizes goes to zero. The study clearly identifies the impact of level-1 and level-2 sample sizes on the standard errors and test statistic of the MUML procedure. Analytical results explain previous simulation results and will guide the design or data collection for the future applications of MUML.This research was supported by NSF Grant DMS04-37167.We thank Dr.Bengt Muthén for providing key references. We are also grateful to three expert reviewers for their constructive comments that have led the paper to an improvement over the previous version.This revised article was published online in August 2005 with the PDF paginated correctly.     

Genetic Evaluation and Counseling of Couples with Recurrent Miscarriage: Recommendations of the National Society of Genetic Counselors

The objective of this document is to provide recommendations for genetic evaluation and counseling of couples with recurrent miscarriage (RM). The recommendations are the opinions of the multidisciplinary Inherited Pregnancy Loss Working Group (IPLWG), with expertise in genetic counseling, medical genetics, maternal fetal medicine, internal medicine, infectious disease, cytogenetics, and coagulation disorders. The IPLWG defines RM as three or more clinically recognized consecutive or non-consecutive pregnancy losses occurring prior to fetal viability (<24 weeks gestation). These recommendations are provided to assist genetic counselors and other health care providers in clinical decision-making, as well as to promote consistency of patient care, guide the allocation of medical resources, and increase awareness of the psychosocial and cultural issues experienced by couples with RM. The IPLWG was convened with support from the March of Dimes Western Washington State Chapter and the University of Washington Division of Medical Genetics. The recommendations are U.S. Preventive Task Force Class III, and are based on clinical experiences, review of pertinent English-language published articles, and reports of expert committees. This document reviews the suspected causes of RM, provides indications for genetic evaluation and testing, addresses psychosocial and cultural considerations, and provides professional and patient resources. These recommendations should not be construed as dictating an exclusive course of medical management, nor does the use of such recommendations guarantee a particular outcome. The professional judgment of a health care provider, familiar with the circumstances of a specific case, should always supersede these recommendations.