Publications by authors named "Johannes A Landsheer"

Objectives: The focus of this study is the classification accuracy of the Montreal Cognitive Assessment (MoCA) for the detection of cognitive impairment (CI). Classification accuracy can be low when the prevalence of CI is either high or low in a clinical sample. A more robust result can be expected when avoiding the range of test scores within which most classification errors are expected, with adequate predictive values for more clinical settings.

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Background: although the existence of inconclusive medical test results or bio-markers is widely recognized, there are indications that this inherent diagnostic uncertainty is sometimes ignored. This paper discusses three methods for defining and determining inconclusive medical test results, which use different definitions and differ in clinical relevance.

Methods: the TG-ROC (two graphs receiver operating characteristics) method is the easiest to use, while the grey zone method and the uncertain interval method require more extensive calculations.

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Often, for medical decisions based on test scores, a single decision threshold is determined and the test results are dichotomized into positive and negative diagnoses. It is therefore important to identify the decision threshold with the least number of misclassifications. The proposed method uses trichotomization: it defines an Uncertain Interval around the point of intersection between the two distributions of individuals with and without the targeted disease.

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In this power study, ANOVAs of unbalanced and balanced 2 x 2 datasets are compared (N = 120). Datasets are created under the assumption that H1 of the effects is true. The effects are constructed in two ways, assuming: 1.

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The effectiveness of Fluvoxamine was compared to that of Cognitive Therapy (CT) in a 12-week randomized controlled trial (RCT) in 48 patients with obsessive-compulsive disorder (OCD), who were treatment-resistant to a previous behavior therapy (BT). A considerable amount of patients did not comply with the assigned treatment and switched treatments. The aim of this study was to identify patient characteristics predictive of assignment compliance and to study whether these characteristics were related to outcome.

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Although it is well known that during adolescence the delinquent involvement of females is consistently less when compared to male involvement, it remains an important question whether the development of delinquency has a similar trajectory for both sexes. The main hypothesis tested is whether sex differences in delinquency, specifically growth, peak age, and decline, are constant. An autoregression model in continuous time, implemented as a structural equation model, is used for the description of the development of delinquency in males and females.

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This study of male and female adolescent delinquency trajectories focuses on the prediction of late adolescence delinquency, based on earlier delinquency and social support. In this 3-wave longitudinal survey, 270 Dutch adolescents (113 males and 157 females) ages 12 to 14, were followed for a period of 6 years. For males, the level of delinquent activity in late adolescence strongly depends on earlier delinquent activities (R2 = .

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The computer program Fractional Design Wizard creates fractional factorial designs that are cost-effective and especially useful for discarding irrelevant factors from a large number of possible candidates. The program is intended for researchers who are relatively new to the field of fractional design and who want to acquaint themselves with the use of fractions for the reduction of large experimental designs. Fractional designs allow estimation of main effects, and sometimes two-way interactions, without one's having to examine all treatment conditions.

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