نتایج جستجو برای: misclassification

تعداد نتایج: 4685  

Journal: :Human heredity 2009
K F Cheng W J Lin

Differential Misclassification of genotype may cause usual tests producing spurious gene-disease associations or unable to detect important associations. To control for the resulting bias, many model-based approaches have been proposed using validation data. However, the effects of joint misclassification of genotype and environmental exposure in studies of gene-environment interaction are stil...

Journal: :Epigenomics 2017
Linda Valeri Sarah L Reese Shanshan Zhao Christian M Page Wenche Nystad Brent A Coull Stephanie J London

AIMS Assessing whether epigenetic alterations mediate associations between environmental exposures and health outcomes is increasingly popular. We investigate the impact of exposure misclassification in such investigations. MATERIALS & METHODS We quantify bias and false-positive rates due to exposure misclassification in mediation analysis and assess the performance of the simulation extrapol...

Journal: :American journal of epidemiology 1985
S Greenland J M Robins

The authors examine some recently proposed criteria for determining when to adjust for covariates related to misclassification, and show these criteria to be incorrect. In particular, they show that when misclassification is present, covariate control can sometimes increase net bias, even when the covariate would have been a confounder under perfect classification, and even if the covariate is ...

1994
Michael J. Pazzani Christopher J. Merz Patrick M. Murphy Kamal M. Ali Timothy Hume Clifford Brunk

We explore algorithms for learning classification procedures that attempt to minimize the cost of misclassifying examples. First, we consider inductive learning of classification rules. The Reduced Cost Ordering algorithm, a new method for creating a decision list (i.e., an ordered set of rules) is described and compared to a variety of inductive learning approaches. Next, we describe approache...

1999
Moon Kim Ravi Shukla

Mutual funds are usually classified based on their stated objectives. If the stated objectives are not the actual objectives the funds pursue, conclusions drawn by investors and researchers based on the stated objectives will be misleading. This study classifies funds based on their attributes (characteristics, investment style, and risk/return measures). We find that the stated objectives of m...

ضمیری, آزاده, فقیه زاده, سقراط, نقی‌زاده, محمدمهدی, گرشاسبی, احیاء,

Background and Objective: Gestational diabetes is one of the most common metabolic disorders during pregnancy. In order to find out a simple and cost effective method with acceptable sensitivity and specificity, fasting plasma glucose (FPG) and one hour 50-g glucose challenge test (OGCT) were compared in patients with gestational diabetes mellitus (GDM). Materials and Methods: In this prospecti...

2012
Hannah Castro Deenan Pillay Caroline Sabin David T Dunn

BACKGROUND Estimates of the prevalence of transmitted HIV drug resistance (TDR) in a population are derived from resistance tests performed on samples from patients thought to be naïve to antiretroviral treatment (ART). Much of the debate over reliability of estimates of the prevalence of TDR has focused on whether the sample population is representative. However estimates of the prevalence of ...

2015
Robert L. Schmidt Joely A. Straseski Kalani L. Raphael Austin H. Adams Christopher M. Lehman Endlich Nicole

BACKGROUND The Jaffe and enzymatic methods are the two most common methods for measuring serum creatinine. The Jaffe method is less expensive than the enzymatic method but is also more susceptible to interferences. Interferences can lead to misdiagnosis but interferences may vary by patient population. The overall risk associated with the Jaffe method depends on the probability of misclassifica...

2017
S. van Doorn T. B. Brakenhoff K. G. M. Moons F. H. Rutten A. W. Hoes R. H. H. Groenwold

Background: Research on prognostic prediction models frequently uses data from routine healthcare. However, potential misclassification of predictors when using such data may strongly affect the studied associations. There is no doubt that such misclassification could lead to the derivation of suboptimal prediction models. The extent to which misclassification affects the validation of existing...

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