The Experts below are selected from a list of 12 Experts worldwide ranked by ideXlab platform
Donald B Rubin - One of the best experts on this subject based on the ideXlab platform.
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the analysis of repeated measures data on Schizophrenic Reaction times using mixture models
Statistics in Medicine, 1995Co-Authors: Thomas R Belin, Donald B RubinAbstract:Reaction times for Schizophrenic individuals in a simple visual tracking experiment can be substantially more variable than for non-Schizophrenic individuals. Current psychological theory suggests that at least some of this extra variability arises from an attentional lapse that delays some, but not all, of each Schizophrenic's Reaction times. Based on this theory, we pursue models in which measurements from non-Schizophrenics arise from a normal linear model with a separate mean for each individual, whereas measurements from Schizophrenics arise from a mixture of (i) a component analogous to the distribution of response times for non-Schizophrenics and (ii) a mean-shifted component. We fit four mixture models within this framework, where the distinctions between models arise from assumptions about the variance of the shifted observations and the exchangeability of Schizophrenic individuals. Some of these models can be fit by maximum likelihood using the EM algorithm, and all can be fit using the ECM algorithm, where the covariance matrices associated with the parameters are calculated by the SEM and SECM algorithms, respectively. Bayesian model monitoring using posterior predictive checks is invoked to discard models that fail to reproduce certain observed features of the data and to stimulate the development of better models.
Thomas R Belin - One of the best experts on this subject based on the ideXlab platform.
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the analysis of repeated measures data on Schizophrenic Reaction times using mixture models
Statistics in Medicine, 1995Co-Authors: Thomas R Belin, Donald B RubinAbstract:Reaction times for Schizophrenic individuals in a simple visual tracking experiment can be substantially more variable than for non-Schizophrenic individuals. Current psychological theory suggests that at least some of this extra variability arises from an attentional lapse that delays some, but not all, of each Schizophrenic's Reaction times. Based on this theory, we pursue models in which measurements from non-Schizophrenics arise from a normal linear model with a separate mean for each individual, whereas measurements from Schizophrenics arise from a mixture of (i) a component analogous to the distribution of response times for non-Schizophrenics and (ii) a mean-shifted component. We fit four mixture models within this framework, where the distinctions between models arise from assumptions about the variance of the shifted observations and the exchangeability of Schizophrenic individuals. Some of these models can be fit by maximum likelihood using the EM algorithm, and all can be fit using the ECM algorithm, where the covariance matrices associated with the parameters are calculated by the SEM and SECM algorithms, respectively. Bayesian model monitoring using posterior predictive checks is invoked to discard models that fail to reproduce certain observed features of the data and to stimulate the development of better models.
Harold Kaplan - One of the best experts on this subject based on the ideXlab platform.
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THE Schizophrenic Reaction WITH PSYCHOPATHIC FEATURES: CLINICAL CHARACTERISTICS AND RESPONSE TO THERAPY
2015Co-Authors: Harold KaplanAbstract:.1 In 1888 Koch changed the name of this pathological entity to constitutional psychopathic inferiority. "Psychopathy" has been used as a "wastebasket" term since its introduction into the psychiatric nosology because its clinical characteristics and limits are so poorly defined. The term as used today describes "various inadequacies and deviations in the personality structure of individuals . . . the defect existing primarily in the conative, emotional and characterological aspects of the personality." 2 As a result of the vagueness of the concept of psychopathy, many patients have been classified as psychopathic who actually were neurotic or psychotic with psychopathic symptoms. Karpman,3 in search of a more specific definition of the boundaries of psychopathy, has divided it into two distinct subtypes: secondary, or symptomatic, psy¬ chopathy, cases of which compromise 85% of the total number, and primary, idiopathic, or essential psychopathy (anethopathy), representing the remaining 15%. In the first subdivision are included all those cases in which, in terms of overt behavior, the disorder seems to be classic psychopathy but in which psychogt nie determinants are easily elicited and the psychopathic behavior reveals itself to be a "specific conditioned Reaction." Under primary psychopathy are included patients in whom careful study fails to reveal "any deep psychic motivation" for their acting-out behavior. This report is concerned with a study of a group of patients falling into Karpman's symptomatic class of psychopathy, i. e., patients From the Neuropsychiatric Service, Veterans Administration Hospital, Bronx, N. Y. Reviewed in the Veterans Administration and published with the approval of the Chief Medical Director. The statements and conclusions published by the author are a result of his own study and do not necessarily reflect the opinion or policy of the Veterans Administration. 1. Prichard, J. C.: Treatise of Insanity, London, Sherwood, Gilbert and Piper, 1835.
Erik Strömgren - One of the best experts on this subject based on the ideXlab platform.
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Autism: Core of the Schizophrenic Reaction
What Is Schizophrenia?, 1991Co-Authors: Erik StrömgrenAbstract:The question in the title of this book can be answered in different ways. It may be understood as aiming at some definition, maybe obtained by a consensus, circumscribing a group of individuals who can be said to belong to a special class, defined by means of clear criteria that should enable everybody working clinically with Schizophrenics to know fairly exactly what kind of individual is meant by the definition. Such a consensus would, however, still not tell us what schizophrenia really is. The definition would probably say nothing about the causes and development of the disorder. The consensus definition would just work as a tool for understanding among those who work with Schizophrenics, some of whom would, however, regard the definition as being too broad, and others as being too narrow. At the present state of our knowledge of the causes of schizophrenia viewpoints concerning etiology differ greatly.
Ph. D - One of the best experts on this subject based on the ideXlab platform.
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Homosexuality and Heterosexuality in Identical Twins
2015Co-Authors: J. D. Rainer, A. Mesnikoff, L. C. Kolb, A. Carr, Ph. DAbstract:T » VALUE of the twin study method has been demonstrated as a means of ap-proaching the study o £ genetic determi-nants of the mental disorders. Kallmann's1 studies, which disclosed the concordant oc-currence of the Schizophrenic Reaction in a large series of one-egg twins as contrasted to the low concordance in two-egg twins and siblings, are a model example of this type of investigation. Such studies have concerned themselves largely with the concordance of similar types of personality organization. In its large context the following presentation represents the initial step in a series of studies directed to examining those factors responsible for the divergent development of behavioral traits in identical twins. It utilizes a variation of the co-twin control method which consists in observing selected pairs of one-egg twins whose physiological Reactions and psychological adaptations may be compared under different life con-ditions. The present design is arranged to examine identical twin pairs with divergent development using current physical and biological (biochemical and tissue exami
