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991.
Avoiding degeneracy in multidimensional unfolding by penalizing on the coefficient of variation 总被引:2,自引:0,他引:2
Frank?M.?T.?A.?BusingEmail author Patrick?J.?K.?Groenen Willem?J.?Heiser 《Psychometrika》2005,70(1):71-98
Multidimensional unfolding methods suffer from the degeneracy problem in almost all circumstances. Most degeneracies are easily recognized: the solutions are perfect but trivial, characterized by approximately equal distances between points from different sets. A definition of an absolutely degenerate solution is proposed, which makes clear that these solutions only occur when an intercept is present in the transformation function. Many solutions for the degeneracy problem have been proposed and tested, but with little success so far. In this paper, we offer a substantial modification of an approach initiated bythat introduced a normalization factor based on thevariance in the usual least squares loss function. Heiser unpublishedthesis, (1981) and showed that the normalization factor proposed by Kruskal and Carroll was not strong enough to avoid degeneracies. The factor proposed in the present paper, based on the coefficient of variation, discourages or penalizes nonmetric transformations of the proximities with small variation, so that the procedure steers away from solutions with small variation in the interpoint distances. An algorithm is described for minimizing the re-adjusted loss function, based on iterative majorization. The results of a simulation study are discussed, in which the optimal range of the penalty parameters is determined. Two empirical data sets are analyzed by our method, clearly showing the benefits of the proposed loss function.The authors would like to thank the editor, an associate editor, and three reviewers for their valuable comments and suggestions to improve the quality of this work.This revised article was published online in August 2005 with the PDF paginated correctly. 相似文献
992.
Jeffrey?A.?AndersonEmail author Rhonda?D.?Meyer W.?Patrick?Sullivan Eric?R.?Wright 《Journal of child and family studies》2005,14(4):505-520
Researchers and practitioners have questioned how the implementation of a system of care influences the broader context of
children's social services within a community. We examined the impact that the Dawn Project system of care had on children's
services in Marion County, Indiana. A series of semi-structured interviews were conducted in order to gain a broad understanding
of stakeholder perspectives related to how system-level and other community leaders viewed system of care influences. Qualitative
analyses uncovered several common themes including positive impact at the community level, challenges to implementation, and
feelings of ambivalence related to program impact. Results were generally positive and suggested that most respondents saw
core system of care principles beginning to emerge within the community related to the establishment of the care system. In
addition, challenges to implementing the system of care also were uncovered, including some underlying resistance to system-level
changes. Implications from our study highlight the importance of continuously working to enhance strengths and collaboration
among systems, integrate and coordinate across systems and services, and authentically involve families at all levels. 相似文献
993.
Conscious intention and motor cognition 总被引:1,自引:0,他引:1
Haggard P 《Trends in cognitive sciences》2005,9(6):290-295
The subjective experience of conscious intention is a key component of our mental life. Philosophers studying 'conscious free will' have discussed whether conscious intentions could cause actions, but modern neuroscience rejects this idea of mind-body causation. Instead, recent findings suggest that the conscious experience of intending to act arises from preparation for action in frontal and parietal brain areas. Intentional actions also involve a strong sense of agency, a sense of controlling events in the external world. Both intention and agency result from the brain processes for predictive motor control, not merely from retrospective inference. 相似文献
994.
Probabilistic grammars for natural languages 总被引:1,自引:0,他引:1
Patrick Suppes 《Synthese》1970,22(1-2):95-116
995.
Patrick Suppes 《Synthese》1966,16(1):74-85
Sans résuméJe désire remercier Jean et Claudine Donio pour la traduction de cet article à partir du manuscrit anglais. 相似文献
996.
Matthew J. O’Brien Patrick W. Romani Wendy K. Berg David P. Wacker 《Behavioral Interventions》2023,38(1):62-79
Following the failure of applications of differential reinforcement (DR), the effects of reinforcement delivered noncontingently (NCR) on task disengagement and task completion were evaluated within reversal designs for three children with autism spectrum disorder. In Experiment 1, we compared DR and NCR schedules that combined positive and negative reinforcement. In Experiment 2, we replicated the results of Experiment 1 and then evaluated NCR schedules composed solely of negative reinforcement and NCR schedules that combined negative reinforcement with high-or low-preferred stimuli. In Experiment 3, we further analyzed NCR schedules that included different types and qualities of positive reinforcement, but without the inclusion of negative reinforcement. The results showed that NCR schedules using positive reinforcers can be effective as a treatment for task disengagement, but the type and preference of the reinforcer can alter effectiveness. These results are interpreted in terms of the motivating operations associated with task disengagement. 相似文献
997.
Timothy R. Vollmer Patrick R. Progar Joseph S. Lalli Carole M. Van Camp Barbara J. Sierp Carrie S. Wright Julia Nastasi Kevin J. Eisenschink 《Journal of applied behavior analysis》1998,31(4):529-542
We compared the effects of extinction (EXT) and fixed-time (FT) schedules as treatment for severe problem behavior displayed by 3 individuals with developmental disabilities. First, functional analyses identified the reinforcers maintaining aberrant behavior for all 3 individuals. Next, EXT and FT schedules were compared using a multielement design. During EXT, the reinforcer maintaining problem behavior was withheld. During FT, the reinforcers were presented response independently at preset intervals. Results showed that FT schedules were generally more effective than EXT schedules in reducing aberrant behavior. FT schedules may be used in situations when extinction-induced phenomena are problematic. 相似文献
998.
999.
David Patrick Houghton 《Political psychology》1998,19(2):279-303
Established models of the domestic policymaking process accord some role to the individual decision-maker, but they usually fail to show how policy decisions are ultimately influenced by the character of the information available to the policymakers concerned. Drawing on one prominent model of decision-making developed by analysts of foreign policy—the analogical reasoning approach—this article proposes that individual-level approaches are most useful in domestic policy analysis where decision-makers must confront a discrete policy "episode" in which perceived levels of cognitive uncertainty and ambiguity are high. An analysis of decision-making by political leaders during the 1967 Detroit riots reveals that these leaders made widespread use of historical analogies at various stages of the policymaking process. Policymakers can probably be expected to rely on analogizing under circumstances and contexts that make cognitive demands similar to those observed in the Detroit case. 相似文献
1000.
Patrick Bonin Michel Fayol Jean-Emile Gombert 《International journal of psychology》1998,33(4):269-286
Unlike speech production, lexical access in written production has not systematically been investigated experimentally. Four experiments were run on literate adults to support the view that although the spoken and written language production systems may obviously share some processing levels, they also both have some specific processing components. The general findings provide evidence for such a view and are discussed in the framework of studies in verbal production conducted on normals and on brain-damaged patients. 相似文献