Accuracy Tests (accuracy + test)

Distribution by Scientific Domains

Selected Abstracts

Fine-needle aspiration cytology in the diagnosis of superficial lymphadenopathy: a 5-year Brazilian experience

M.Sc., Marcos Roberto Martins M.D.
Abstract To determine the accuracy of fine-needle aspiration (FNA) in the diagnostic assessment of lymphadenopathies, a retrospective study was conducted on 627 cases of FNA of the lymph nodes performed at Department of Pathology, UNIFESP (Federal University of São Paulo), between 1997 and 2001. Cytology results were compared to the results of biopsies if available. The cytological diagnosis was unsatisfactory in 14.7% of cases, positive in 46%, and negative in 39.3%. Among the positive cases, 79.4% were classified as metastases, 14.2% as lymphoma, and 6.4% as indeterminate. Anatomopathological exams for the determination of cytohistological correlation were available in 218 of the 627 cases. There were three (1.88%) false-negative and two (1.25%) false-positive cases. Accuracy tests revealed 97.41% sensitivity, 95.45% specificity, and 96.88% efficacy, with cytohistological agreement being almost perfect (, = 0.92). The high accuracy of this study based only on cytomorphological criteria associated to the variety of malignant neoplasias diagnosed by the procedure demonstrates its relevance on patient care, especially in areas of limited financial resources. Diagn. Cytopathol. 2006; 34:130,134. © 2006 Wiley-Liss, Inc. [source]

Technical note: Usability evaluation of the modified CIE1976 Uniform-Chromaticity scale for assessing image quality of visual display monitors

WookGee Lee
White uniformity indicates the degree of uniform distribution of white color across the display screen and is one of the important inspection factors determining the image quality of a visual display unit (VDU). Experiments in which participants were confronted with 6 evaluation points embedded in 3 measurement groups on a VDU screen were conducted to gather the psychophysical data that include the levels of white uniformity obtained from participants and a colorimetric system (CA-100). In an accuracy test, 37.12% of the participants showed the same conclusion led by the original CIE1976 criteria, and 62.88% of the participants showed the same conclusion led by the modified equation. In magnitude estimation evaluating the display's white uniformity, the magnitude score of the modified equation (0.36) was significantly larger than that of the original equation (0.32). It was concluded that the modified equation is more sensitive to the change of white uniformity. © 2003 Wiley Periodicals, Inc. Hum Factors Man 13: 85,95, 2003. [source]

Meta-analysis of the nonword reading deficit in specific reading disorder

DYSLEXIA, Issue 3 2006
Julia A. Herrmann
Abstract A meta-analysis was conducted to investigate whether specific reading disorder (SRD) groups demonstrate a deficit in using phonological recoding strategies. Thirty-four studies were reviewed that had compared the nonword reading performances of SRD groups with reading-level matched (RL) control groups. The average nonword reading difference between groups across the total number of studies was moderate (d=0.65, N=2865). Three predictors of the size of group differences in nonword reading ability were identified. Studies that used passage reading tests to match groups for reading level found significantly less evidence for nonword reading deficits than studies that used word-level reading accuracy tests. Secondly, there was a significant positive relationship between group differences in intelligence level (SRD-RL control group) and effect sizes. Finally, group differences in age showed a significant negative association with effect magnitudes. The mean age, reading level and intelligence level of groups did not significantly predict nonword reading outcomes. It was concluded that there was evidence for nonword reading deficits in SRD groups, consistent with the claim that deficient development of phonological recoding strategies is a leading cause of reading difficulties. Copyright © 2006 John Wiley & Sons, Ltd. [source]


Valentina Corradi
We introduce block bootstrap techniques that are (first order) valid in recursive estimation frameworks. Thereafter, we present two examples where predictive accuracy tests are made operational using our new bootstrap procedures. In one application, we outline a consistent test for out-of-sample nonlinear Granger causality, and in the other we outline a test for selecting among multiple alternative forecasting models, all of which are possibly misspecified. In a Monte Carlo investigation, we compare the finite sample properties of our block bootstrap procedures with the parametric bootstrap due to Kilian (Journal of Applied Econometrics 14 (1999), 491,510), within the context of encompassing and predictive accuracy tests. In the empirical illustration, it is found that unemployment has nonlinear marginal predictive content for inflation. [source]

Analysis of 3D problems using a new enhanced strain hexahedral element

P. M. A. Areias
Abstract The now classical enhanced strain technique, employed with success for more than 10 years in solid, both 2D and 3D and shell finite elements, is here explored in a versatile 3D low-order element which is identified as HIS. The quest for accurate results in a wide range of problems, from solid analysis including near-incompressibility to the analysis of locking-prone beam and shell bending problems leads to a general 3D element. This element, put here to test in various contexts, is found to be suitable in the analysis of both linear problems and general non-linear problems including finite strain plasticity. The formulation is based on the enrichment of the deformation gradient and approximations to the shape function material derivatives. Both the equilibrium equations and their variation are completely exposed and deduced, from which internal forces and consistent tangent stiffness follow. A stabilizing term is included, in a simple and natural form. Two sets of examples are detailed: the accuracy tests in the linear elastic regime and several finite strain tests. Some examples involve finite strain plasticity. In both sets the element behaves very well, as is illustrated in numerous examples. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Asymmetry in the link between the yield spread and industrial production: threshold effects and forecasting

Ivan Paya
Abstract We analyse the nonlinear behaviour of the information content in the spread for future real economic activity. The spread linearly predicts one-year-ahead real growth in nine industrial production sectors of the USA and four of the UK over the last 40 years. However, recent investigations on the spread,real activity relation have questioned both its linear nature and its time-invariant framework. Our in-sample empirical evidence suggests that the spread,real activity relationship exhibits asymmetries that allow for different predictive power of the spread when past spread values were above or below some threshold value. We then measure the out-of-sample forecast performance of the nonlinear model using predictive accuracy tests. The results show that significant improvement in forecasting accuracy, at least for one-step-ahead forecasts, can be obtained over the linear model. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Virtobot,a multi-functional robotic system for 3D surface scanning and automatic post mortem biopsy

Lars Christian Ebert
Abstract Background The Virtopsy project, a multi-disciplinary project that involves forensic science, diagnostic imaging, computer science, automation technology, telematics and biomechanics, aims to develop new techniques to improve the outcome of forensic investigations. This paper presents a new approach in the field of minimally invasive virtual autopsy for a versatile robotic system that is able to perform three-dimensional (3D) surface scans as well as post mortem image-guided soft tissue biopsies. Methods The system consists of an industrial six-axis robot with additional extensions (i.e. a linear axis to increase working space, a tool-changing system and a dedicated safety system), a multi-slice CT scanner with equipment for angiography, a digital photogrammetry and 3D optical surface-scanning system, a 3D tracking system, and a biopsy end effector for automatic needle placement. A wax phantom was developed for biopsy accuracy tests. Results Surface scanning times were significantly reduced (scanning times cut in half, calibration three times faster). The biopsy module worked with an accuracy of 3.2 mm. Discussion Using the Virtobot, the surface-scanning procedure could be standardized and accelerated. The biopsy module is accurate enough for use in biopsies in a forensic setting. Conclusion The Virtobot can be utilized for several independent tasks in the field of forensic medicine, and is sufficiently versatile to be adapted to different tasks in the future. Copyright © 2009 John Wiley & Sons, Ltd. [source]