نتایج جستجو برای: bias correction factors

تعداد نتایج: 1328407  

Journal: :The British journal of mathematical and statistical psychology 2010
Spiridon Penev Tenko Raykov

This paper is concerned with the reliability of weighted combinations of a given set of dichotomous measures. Maximal reliability for such measures has been discussed in the past, but the pertinent estimator exhibits a considerable bias and mean squared error for moderate sample sizes. We examine this bias, propose a procedure for bias correction, and develop a more accurate asymptotic confiden...

2008
Duane T. Wegener Richard E. Petty RICHARD E. PETTY

Life often presents us with situations in which it is important to assess the “true” qualities of a person or object, but in which some factor(s) might have affected (or might yet affect) our initial perceptions in an undesired way. For example, in the Reginald Denny case following the 1993 Los Angeles riots, jurors were asked to determine the guilt or innocence of two African-American defendan...

2008
AARON T. PEARSE

Incomplete detection of all individuals leading to negative bias in abundance estimates is a pervasive source of error in aerial surveys of wildlife, and correcting that bias is a critical step in improving surveys. We conducted experiments using duck decoys as surrogates for live ducks to estimate bias associated with surveys of wintering ducks in Mississippi, USA. We found detection of decoy ...

2016
M. Ethan MacDonald Nils D. Forkert G. Bruce Pike Richard Frayne Heye Zhang

PURPOSE Volume flow rate (VFR) measurements based on phase contrast (PC)-magnetic resonance (MR) imaging datasets have spatially varying bias due to eddy current induced phase errors. The purpose of this study was to assess the impact of phase errors in time averaged PC-MR imaging of the cerebral vasculature and explore the effects of three common correction schemes (local bias correction (LBC)...

ژورنال: مجله دندانپزشکی 2008
باشی زاده فخار, حوریه, شاکری, ناصر, شیرازی, علیرضا, طلایی‌پور, احمدرضا, قاسم‌زاده, علی, نوروزپور, یاسر,

Background and Aim: Image distortion is one of the major problems in panoramic radiography. Horizontal and vertical correction factors could be determined for more efficient clinical applications. The purpose of this study was to determine horizontal and vertical correction factors in panoramic radiography.Materials and Methods: In this test evaluation study in which an asymetric mandibular pha...

1996
Yutaka KANO

Takeuchi [37], Takeuchi and Akahira [38] and Pfanzagl [27] among others proved that any rst-order ecient estimators are second-order ecient. Many authors e.g., Ghosh [15], have conjectured that any third-order ecient estimators are fourth-order ecient. Based on concentration probability of estimators about a true parameter, this paper gives a positive answer to the conjecture in a curved expone...

2014
Chao Li Eva Sinha Daniel E. Horton Noah S. Diffenbaugh Anna M. Michalak

Bias correction of meteorological variables from climate model simulations is a routine strategy for circumventing known limitations of state-of-the-art general circulation models. Although the assessment of climate change impacts often depends on the joint variability of multiple variables, commonly used bias correction methodologies treat each variable independently and do not consider the re...

2012
I. Haddeland

Due to biases in the output of climate models, a bias correction is often needed to make the output suitable for use in hydrological simulations. In most cases only the temperature and precipitation values are bias corrected. However, often there are also biases in other variables such as radiation, humidity and wind speed. In this study we tested to what extent it is also needed to bias correc...

Journal: :Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 2016
Janet R Vos Jan C Oosterwijk Cora M Aalfs Matti A Rookus Muriel A Adank Annemarie H van der Hout Christi J van Asperen Encarna B Gómez Garcia Arjen R Mensenkamp Agnes Jager Margreet G E M Ausems Marian J Mourits Geertruida H de Bock

BACKGROUND Paternal transmission of a BRCA mutation has been reported to increase the risk of breast cancer in offspring more than when the mutation is maternally inherited. As this effect might be caused by referral bias, the aim of this study was to assess the parent-of-origin effect of the BRCA1/2 mutation on the breast cancer lifetime risk, when adjusted for referral bias. METHODS A Dutch...

Journal: :Journal of magnetic resonance imaging : JMRI 2009
Zin Yan Chua Weili Zheng Michael W L Chee Vitali Zagorodnov

PURPOSE To investigate inconsistencies between common performance measures for bias field correction reported in several recent studies and propose a solution. MATERIALS AND METHODS A set of synthetic images of a normal brain from the Montréal Simulated Brain Database (SBD) was processed using two bias field correction algorithms. The parameters of these algorithms were varied and the resulti...

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